osservatorio astronomico di roma graphical user interface for lbc obs reference manual version date page 1.2 22 a
Osservatorio Astronomico di Roma
Graphical User Interface for LBC OBs
Reference Manual
Version
Date
Page
1.2
22 Apr 2004
58 of 58
Large Binocular Camera
Graphical User Interface for LBC Observing Blocks
Reference Manual
Author: Stefano Gallozzi
date: 2004-04-22
email: [email protected]
Copyright © 2004, Stefano Gallozzi & LBC-Team
Graphical User Interface for LBC Observing Blocks,
Reference Manual
Table of Contents
GUI, Graphical User Interface – 1.
Observing Blocks – 2.
Folder Operations – 3.
OB Operations – 4.
Observing Plans – 5.
OP Operations – 6.
Dithering Calculator – 7.
Exposure Time Calculator – 8.
Interactive Pointing – 9.
1. GUI, GRAPHICAL USER INTERFACE
The GUI is a Java multiplatform application designed to be very user
friendly in all its operations
Goals of the application are:
- Create a standard for the LBC/LBT ObservingBlock (OB) in a database
XML format, compatible with the AVOTables XML standards
- View/Modify a single OB in all its fields
- Concatenate more Observing Bock together in order to create an
xml-Observing Plan (OP)
1.1. OB/Plan XML-file Format
The XML Markup Language is a web file format created to organize in a
database-like format all type of data; the advantage of using this
data architecture is the great flexibility of the web resource in
conjunction with the stability of a database approach.
It' possible to define a standard definition of variables types with
relative intervals of the parameters inserted in the xml-file
(XSD-schema-file).
This application is designed to be totally compatible with the VOTable
XML standards.
Lots of Programming Languages libraries are availables to interface
with XML (we use SAX=Simple API for XML), but also AXIS is a good
choise for web services.
1.2. GUI Organization
The GUI is organized in three main TabPanel divided by topics (view
three following pics):
- Target Package Panel (is a slice representing pointing and
observation parameters: RA-Dec, Target Name, Proper Motion, ...)
- Observation Description (is a slice representing all the instrument
parameters for the observation: dithering pattern, ETC, ...)
- Constrain Sets (is a slide as ESO-Style to constrain the observation
by some particular parameter: wheather condition, seeing, exposure
time, ...)
1.3. GUI Operations on OB/OP
It's possible to perform some operation on OB and Plan:
*
Create OB-OP (it' also possible to create a directory where to
store all data)
*
Copy/Move/Delete OB-OP
*
Print/Export to PS file format an OB-OP
*
View/Modify the content of OB-OP
*
Save the data in a file OB-OP (xml-format)
These operations are possible thanks to special and specified
JavaButtons and JavaMenus located in the top ToolBar.
There are three type of button/menu groups (see following picture):
Folder Buttons (yellow)
Plan Buttons (red)
OB Buttons (green)
It's possible to perform some special operations on the data inserted:
*
Dithering Pattern Calculation
*
Exposure Time Calculation
*
Interactive Pointing
These operations are carried on data and the final results are
inserted in the Observing Block File, see below.
2. OBSERVING BLOCK
Each Observing Block for the LBC camera of the LBT Telescope is saved
in a XML-databse file (extension .ob).
To the ob-xml file is associated a ob-schema file (extension .xsd),
which represents the variable declaration and structure of the
relative xml.
The file is subsequently processed by a standard C/C++-library to
extract the variables and perform the necessary instrument operations.
This C/C++ library is included in the GUI package.
2.1. VARIABLE DEFINITION AND OB STRUCTURE
The Observing Block Structure is composed of three top level fields in
the XML-database schema:
i.
LBC_Target field, which represents the relative parameters for the
observation of a specific target.
ii.
LBC_Channel field, which represents the total observation
parameters to customize in the most powerful way possible every
single exposure for the B and R Channel.
iii.
Constrain Sets field, which represents an ESO like way to define
the range for some observation parameters, ie. CSS(Constrain Sets
for Seeing) define an interval for the observation seeing, if the
place seeing values falls inside that interval the observation
should be taken.
Here is a list of all the inserted variables with the respective
meaning:
----------------------------------------
- OBName = Observing block name (string), is the name of the OB as it
appear on the disk (without .ob extension) - (String).
- TargetName = Target Package Name (string), is the name of the
observation target - (String).
- ClassType = Class-type of observation, ie. Standard Star,
Flat-field, Dark, Scientific Object – (String).
- TEC_RA & TEC_DEC = Target Equatorial Coordinates, Right Ascention
and Declination, is the starting point for the observation on the sky
in decimal degree format – (float).
- Equinox = Equinox of coordinates, 1950 or 2000 – (int).
- Offset_RA & Offset_DEC = Offsett in arcsec for RA and Dec, is the
arcsec offsetting from the central RA0-DEC0 position – (float).
- ProperMotion_RA & ProperMotion_DEC = RA DEC Proper Motion, is the
proper motion of an observation target/object in arcsec for RA and Dec
– (float).
- TRACKING, Telescope = Tracking, presetting telescope – (boolean).
Window settings and parameters:
- WXMIN, WXMAX, WYMIN, WYMAX = pixel settings for X-Y window:
X=[1,2048], Y=[1,4600] – (int).
- PDIT = Dithering pattern is the logical operation to calculate the
dither, ie. Random, UserDefined, Spiral, Circular, TBD (string).
- ADIT, SDIT, DITX0 & DITY0 = Dithering Angle, Scale and offset for
X-Y axis, parameters to calculate dithering steps – (float).
- NDIT, DIT0 = Number of dithering offsets and Starting item,
parameters to calculate dithering steps – (int).
- XDIT & YDIT = list of dithering pattern in RA and Dec from the
central RA0,DEC0 position – (array of floats).
--------------------------------------------------------------
and
For B and R Arm there are the same parameters, here's a list:
- PSB & PSR = Master, Slave or Off, what kind of setting must perform
the Channel – (int: OFF=0, MASTER=1, SLAVE=2).
- RA_B & RA_R = Rotation angle for B and R- Arm, is the angle of
rotation for each camera in decimal degree format – (float).
- FocussOffset & FocussStartPosition = keyword which represents the
Offset of each step in the fucus procedure and the Starting position
for each Arm; the Filter used for this operation are the first filter
of the filter list for each Channel with theire own Exposure Time and
number of exposure. The two keyword can be setted with the special
Jframe (see following fig.) accessible by the “Edit Focus” button in
the Observation description - (double).
- Chip1, Chip2, Chip3, Chip4, Shutter = ON/OFF for Chip 1, 2, 3, 4 and
Shutter (boolean).
- ReadOutMode_B & ReadOutMode_R = Read Out Mode, ie. fast and slow
(boolean)
- CCDBin_B & CCDBin_R = CCD Binning Factor, is the bin factor for the
image acquisition – (boolean).
- FilterNumber = Is the Filter number selected (max is 8 for each
channel) – (int).
selected.
- FilterName = Is the name of the Filter selected - (String).
- SingleExpoTime = Is the Single Exposure Time for the observation
with the selected filter – (float).
- Nexpo = Is the number of exposure taken with the selected filter –
(int).
- Focuss = Is a flag for focuss the observation for the selected
filter – (boolean).
- Identifier = Is the identifier for the observation – (string).
- Pipeline = Are the pipeline instructions for the selected
observation – (string).
User hidden parameters:
- ReadOutTime = Read Out Time, is the total time to download the
acquisition image and be ready to take new one – (float).
- TimeOffset = Offsetting Time, is the time necessary to offset the
telescope – (float).
- SEEING = Seeing of the observation, is the real seeing for the
observation, not calculated – (float).
- MOON = Moon Phase of the observation, is the real moon phase for the
observation, not calculated – (int).
Constrain Parameters (like ESO):
- CST = Constrain Sets Timing – (string).
- CSP = Constrain Sets Position – (string).
- CSW = Constrain Sets Weather – (string).
- CSS = Constrain Sets Max Seeing – (String).
- CSF = Constrain Sets Frame – (string).
Additional Parameters:
- OBJECT = Is the name of the Target of Observation – (string).
- OBSID = Is the Identification ID of the Observation – (string).
- PROPID = Is the Proposal Identification ID of the Observation –
(string).
- OBSERVER = Is the name of Observer – (string).
- LBCUSER = Is the name of LBC-USER – (string).
2.2. OB-XML & SCHEMA FILE EXAMPLE
Here is an example of a saved Observing Block with its schema file:
OB XML Example File
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2.3. OB Schema File
OBSERVING BLOCK OB for LBC-LBT
2.4. OB Write-Read C/C++ Library
The C/C++ library distributed with this package was created to perform
basic operation with the XML OB file generated by the GUI:
1.
Write an example OB.
2.
Read an OB file and put its content in a variable structure,
described later.
3.
self-Check utility.
4.
Initializing structure tool.
5.
redirect the output in a standard flow.
Here is the C-variable structure used in the Library:
/*! \struct LBC_TARGET
* Define the Target Variable Structure.
*/
typedef struct {
char *szOBName; /*!Observing Block Name, is the name of the OB without
.ob extension.*/
char *szTargetName; /*!Target Name, is the name of the target of the
observation.*/
char *szClassTypeObs; /*!Class Type of Observation (Dark, Scientific
Object, Standard Star, Flat Field, ecc).*/
double Ra, Dec; /*!RA and DEC Coordinates (decimal degree format)*/
char *szObject; /*!Identifier observation title */
char *szObsID; /*!Unique observation ID */
char *szPropID; /*!Proposal identification */
char *szObserver; /*!Observer Name */
char *szLBCUser; /*!P.I. Name */
// double Offset_Ra, Offset_Dec; /*!RA and DEC Offset (arsec)*/
double ProperMotion_Ra, ProperMotion_Dec; /*! Proper Motion (arsec)*/
int iEquinoxOfCoord; /*!Equinox of Coordinates (1950 or 2000)*/
int fTracking; /*!Tracking, flag for tracking*/
int fTelescope; /*!Preset LBT Telescope, flag for presetting the LBT
Telescope*/
int iWinXMin, iWinXMax; /*!Window X Parameters (pixels)*/
int iWinYMin, iWinYMax; /*!Window Y Parameters (pixels)*/
/*DITHERING PARAMETERS*/
int iNDit; /*!Number of Dithering Offset, number of dithering steps*/
double *XDit, *YDit; /*!X-Y Dithering Steps, from starting point
[RA0,DEC0] (arcsec)*/
} LBC_TARGET;
/*! \struct LBC_FOCUS
* Define the Structure for Focus quantities for each LBC Channel.
*/
typedef struct {
char *szFocusFilterName; /*!Filter Name for focus procedure*/
int iFocusExpoNumber; /*!Number of Exposures for focus*/
double FocusSingleExpoTime; /*!Single Exposure Time for focus*/
double FocusOffset; /*!Focus Offset for each step*/
double FocusStartPosition; /*!Focus starting position*/
} LBC_FOCUS;
/*! \struct LBC_FILTERS
* Define the Structure for each LBC Channel.
*/
typedef struct {
char *szFilterName; /*!Filter Name*/
int iExpoNumber; /*!Number of Exposures, number of exposure for all
dithering steps*/
double SingleExpoTime; /*!Single Exposure Time = (TotalExposureTime /
NExposures) for each Dith step (sec)*/
char *szIdentifier; /*!Identifier for Arm, identifier for Pipeline
Instructions*/
char *szPipeline; /*!Pipeline Instruction, to be inserted in the
keyword*/
} LBC_FILTERS;
/*! \struct LBC_CHANNEL
* Define the Structure for each LBC Channel.
*/
typedef struct {
int iArmSetting; /*!Arm Setting (OFF=0 - MASTER=1 - SLAVE=2)*/
int fReadoutMode; /*!Read-Out Mode, flag for Read-Out Mode (slow=0 -
fast=1)*/
int fChip1, fChip2, fChip3, fChip4; /*!Boolean for Chip turned
ON-OFF*/
int fShutter; /*!Boolean or Shutter ON-OFF*/
double RotAngle; /*!Rotation Angle for Arm (degree)*/
int iCcdBin; /*!CCD Binning, factor for rebin of the image*/
int iNFilters; /*!Number of Filter for Arm (tot FilterNumber = 8)*/
LBC_FOCUS pFocus; /*!Focus Quantities and Parameters */
LBC_FILTERS *pFilter; /*!Filter Vector of iNFilters elements for
Selected Arm */
} LBC_CHANNEL;
/*! \struct LBC_OB
* Define the OB Variable Structure Type
*/
typedef struct {
int fLoaded;
LBC_TARGET LBC_Target;
LBC_CHANNEL B_Arm, R_Arm;
} LBC_OB;
typedef LBC_OB *PLBC_OB; /*!Define Pointer to Main OB-Structure*/
3. FOLDER OPERATIONS
The LBC OB GUI Archiving is organized in the seguent way:
To the top level there are the Folders.
A folder is a User defined directory in a pre-defined path that can
be renamed. This directory can be created by hands through OS commands
or directly by the GUI Interface.
In the directory created the User Interface creates also an ascii fi
le (.descr) with the main Folder parameters (ie.: name and date of
crea
tion).
Inside the Folder are present the Plan XML-archive files which conta
in any Observing Blocks. For each Observing Block inside the plan a
cop
y is created in the Folder. It's possible also to create a single OB
wi
thout connection to any Plan.
3.1. How to Create a new Folder
A new Folder can be created by the User Interface with the Folder Menu
(sub-Item "new Folder"); alternatively you can push the first jButton
(
New Folder) on the top of the GUI. In the window you can choose the
nam
e of the folder and the absolute path where the Folder have to be
putte
n.
You can also use the particular OS system commands to create the
named-
Folder in the right path.
3.2. How to Delete a Folder
A Folder can be deleted directly by the User Interface with the Folder
Menu (sub-Item "delete Folder"); alternatively you can push the
jButton
(Delete Folder) on the top of the GUI. You only have to select the rig
ht Folder.
Be careful when you delete a complete folder, all its content is
define
tly lost.
You can also use the particular OS system commands to delete the
named-
Folder with the right path.
3.3. How to View the Folder Content
To view the content of a Folder you have con load it in the jTree. To
p
erforn this action you have to choose the Folder Menu (sub-Item "Open
F
older"); alternatively you can push the second jButton (Open Folder)
on
the top of the GUI.
When a folder is load the jTree shows its path component, in
particular
it shows the Plan XML Files. And if the directory was created by the U
ser Interface, in the jText-area is displayed the descriptor file of
th
e directory.
3.4. Folder Descriptor Example File
------
Folder Name = ARCHIVIO
Date of Creation = 2003 07 19
------
4. OB OPERATIONS
4.1. How to Create a new OB
To create a new OB it's possible to push on the nineth jButton (new
OB) or selecting the jMenu OBs (sub-Item "New OB"). You can insert the
new OB name and when you confirm your choise all the other fileds in
the mainwindow will be resetted. Anyway no OB will we written on disk
until you won't save it. This is the only way to modify or update the
“PropsalID” and “LBCUser” XML-keyword.
4.2. How to Create a new OB
To save an OB it's possible to push the relative jButton (save OB) or
selecting the jMenu OBs (sub-Item "Save OB"). If a Plan is selected
before a copy of the OB will be inserted in the xml-file of the plan
and all records of the plan will be updated. Before to write the OB on
disk the User Interface perform some calculation and variables check
to be sure you selected the right values (See "OB File Structure Help"
for more details).
4.3. How to Check for Variables inserted in the OB
It's possible to check for variables before saving the OB file; you
only have to push the "validate" button on the right top of the GUI;
if no error is displayed the OB is ready to be saved.
4.4. How to Reset OB fields
It's possible to reset all the values in the OB fields if some error
has occurred, you only have to push on the right top of the GUI the
"reset" button.
4.5. How to Delete an OB
To delete an OB it's possible to push on the relative jButton (delete
OB) or seleting the jMenu OBs (sub-Item "Delete OB").
4.6. How to Copy an OB
To copy an OB it's possible to push on the relative jButton (copy OB)
or seleting the jMenu OBs (sub-Item "copy OB"). You only have to
select the origin and destination OB files.
4.7. How to Open/View OB
To open/view an OB it' s possible to push on the relative jButton
(Open OB) or seleting the jMenu OBs (sub-Item "Open OB"). When the
descriptor file of the OB is displayed in the new window, it's
possible to choose to Load it's parameters in the mainwindow, you only
have to push the "Load Values" jButton.
4.8. How to Confront different OBs in a OP
It's possible to confront more OBs in a OP double clicking in the
jTree on the relative plan. It's displayed a jTable with all the OBs'
records.
4.9. How to Export an OB
To Export a Descriptor file of a OB to a PS format it's possible to
push on the relative jButton (export OB to PS file) or seleting the
jMenu OBs (sub-Item "Export OB to PS File").
4.10. How to Print an OB
It's possible to print the descriptor file of an OB pushing the "print
OB" button or seleting the jMenu OBs (sub-Item "Print OB"). NB: It's
necessary to have a default printer installed and working.
5. Observing Plans
The OB Plan Archives are Xml files used to manage the OB data as a
database.
A plan is inserted in a particular Folder which can contains more
plans and OBs.
The organization of the Plan is described below:
- Plan file (.xml), the real xml database.
- Plan Schema File (.xsd), the schema file to declare the parameters
in the xml file.
- Plan Entry-file (.entry), ascii file which contains the list of all
OBs in the plan.
*
Plan descriptor file (.txt), to be visualized in the jTextArea
of the GUI.
*
In the .xml file is inserted the schema file as a xml-comment to
permit the download and upload of a single plan file.
5.1. XML PLAN Example
######################
# LBC-OB GUI - Plans #
######################
The OB Plan Archives are Xml files used to manage the OB data as a
database.
A plan is inserted in a particular Folder which can contains more
plans and OBs.
The organization of the Plan is described below:
- Plan file (.xml), the real xml database.
- Plan Schema File (.xsd), the schema file to declare the parameters
in the xml file.
- Plan Entry-file (.entry), ascii file which contains the list of all
OBs in the plan.
- Plan descriptor file (.txt), to be visualized in the jTextArea of
the GUI.
In the .xml file is inserted the schema file as a xml-comment to
permit the download and upload of a single plan file.
#########################
# XML PLAN FILE EXAMPLE #
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xsi:schemaLocation="D:\Documents and Settings\Stefano
Gallozzi\Desktop/Plan.xsd">
Gallozzi\Desktop/Plan.xml
Gallozzi\Desktop
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267.D-5725(A)-0001
267.D-5725(A)
Fred Flinstone
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1.899 2.738 3.577 4.416
-21.926 -23.309 -24.148 -24.987 -24.443 -23.899 -23.355
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267.D-5725(A)-0001
267.D-5725(A)
Fred Flinstone
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5.2. TXT OP Entry File Example
Blocco1.ob
Blocco2.ob
5.2. TXT OP Descriptor File Example
------
Plan Name = Plan.xml
Folder Name = D:\Documents and Settings\Stefano\Documenti\ARCHIVIO
Comment = Prova Commento
Owner = Stefano Gallozzi
Date of Creation = 2003-07-19 (today: 2003 07 19)
------
Blocco1.ob
Blocco2.ob
6. OP OPERATIONS
6.1. How to Create a new OP
To create a new Plan it's possible to push on the fourth jButton (new
Plan) or selecting the jMenu Plans (sub-Item "New Plan"). The Window
permits to insert some parameters as the plan name, the Folder
location, the owner, the date of creation and a comment.
6.2. How to Delete an OP
To delete a Plan it's possible to push on the relative jButton (delete
Plan) or seleting the jMenu Plans (sub-Item "Delete Plan").
6.3. How to Copy an OP
To copy a plan it's possible to push on the relative jButton (copy
Plan) or seleting the jMenu Plans (sub-Item "copy Plan"). You only
have to select the origin and destination Plan files.
6.4. How to View an OP
To view a Plan it' s possible to push on the relative jButton (Open
Plan) or seleting the jMenu Plans (sub-Item "Open Plan"). When a plan
is visualized on the jTree, the description file is displayed on the
jText-Area. It's possible to perform some operation:
*
Double click of the mouse on the jTree item corresponding to the
Plan, you visualize a jTable with the Observing Block present in
the relative plan with respective parameters.
*
Right click of the mouse on the jTree item corresponding to the
Plan, you can choose to display all possible operation on the
single plan. A new window is displayed where you can choose to
delete, copy, export Plan descriptor file as PS file, view Plan
and view the single OB of the plan.
6.3. How to Export an OP
To Export a Descriptor file of a Plan to a PS format it's possible to
push on the relative jButton (export Plan to PS file) or seleting the
jMenu Plans (sub-Item "Export Plan to PS File").
7. DITHERING CALCULATOR
Filling up the required fields with right values it's possible to
calculate the dithering offsets for an observation
These roto-translations points of the telescope are from the central
position (see following fig.)Here are the Possible dithering
calculations:
- Random Dithering
- Circular Dithering
- Rectangular Dithering
- User-defined Function
- None
8. EXPOSURE TIME CALCULATOR
8.1. How to Open ETC Panel
In the observation description TabPanel you have to push the one of
the ETC button corresponding on the Filter to calculate to (see
following picture).
8.2. How to Make Calculations
For each filter and dithering steps, it's possible to perform the
Exposure Time Calculator inserting right values of parameters such as
Magnitude Limit, SNR, SkyBackground, Magnitude of Saturation, ecc...
There're three tipe of calculation depending on the input for Total
Exposure Time:
*
get TotalExposureTime from SNR and MagnitudeLimit
*
get SNR from TotalExposureTime and MagnitudeLimit
*
get MagnitudeLimit from SNR and TotalExposureTime
These three calculations are available with one of the following four
quantities fixed:
*
SingleExposureTime
*
Number of Exposures
*
SkyBackground
*
Magnitude of Saturation
As input parameters you also have to select which kind of object would
you like to simulate (i.e. Star, SpiralGalaxy or EllipticalGalaxy),
the Filter, the Airmass, the MoonPhase and the PhotometricAperture. If
you'd like to have a ploto for the filter used, you have to push the
Filter Efficiency button and a new window will appear with the Filter
Efficiency, the Total Efficiency at the selected airmass and the Total
Efficiency in vacuum.
Finally when all physical quantities are set correctly you only have
to push the perform ETC button and all fields will be filled if the
calculation has run.
It's possible to view the resulting simulation and calculation
parameters by clicking on the view detailed parameters label, the
result is a new window with the image of the star/galaxy simulated and
all the calculated parameters (see also WEB implementation of ETC:
http://lbc.mporzio.astro.it ).
8.4. How to Send Data Filter to the GUI
When you have performed a calculation with the right physical
parameters and you wish to send these calculated parameters to the
main GUI window, you have to push the send to mainwindow button: the
selected Filter field will be filled with the calculated parameters
from the ETC. The parameters send to the filter field are the Total
Exposure Time, Single Exposure Time and number of Exposures for that
dithering steps.
8.5. ETC Formulas (A. Grazian)
###########################################
# Exposure Time Calculator (ETC) for LBC. #
###########################################
The preliminary step is to distinguish between Masters Arms and Slave
Arms; the reason why is that the Slave Channel must follow the Master
in order not to get independent exposures.
According with the ditering steps here is the flux diagram of the
exposures.
TETB = Total Exposure Time
SET = Single Exposure Time
NE = Number of Exposures
NDIT = Number of Dithering Steps
ROT = Read-Out Time
if (Channel is Master) TET(master) = SET(master) * NDIT * NE(master)
=> SET(master) = TET(master) / (NDIT * NE(master))
if (Channel is Slave ) TET(slave) = SET(slave) * NDIT * NE(slave) =>
SET(slave) = {[(SET(master) + ROT) * NE(master)] / NE(slave)} - ROT
##########################################################
# FIRST PANEL (TOTAL EXPOSURE TIME)
##########################################################
First case:
given the seeing, the aperture for photometry, the exposure time and
the Signal to Noise ratio, you can compute the magnitude of a source
in the given aperture and the total magnitude, given the aperture
correction.
s=seeing (arcsec)
p=pixel size (arcsec/px)
t=total exposure time (second)
w=photometric aperture diameter (arcsec)
r=ratio between aperture w and seeing s (aperture in seeing units)
A=area (pixel)
M=total magnitude (AB mag)
Ma=magnitude at a given aperture (AB mag)
Ms=magnitude of the sky (AB mag/arcsec**2)
SN=Signal to Noise Ratio
F=total flux of the source in ADU
B=flux of the background (per pixel) in ADU
ZpAirm=magnitude zero point for a given Airmass
Zp=magnitude zero point for Airmass=0.0
Ca=correction aperture (for star, elliptical or spiral galaxy)
n=number of exposures
g=gain (e-/ADU)
a=flat field accuracy for a single exposure
ron=Read Out Noise of LBC (e-/ADU)
p=0.23
a=0.005
ron=2.25
g=2.09
r=w/s
A=3.141592654*(s*r/(2*p))**2
B=t*(p**2)*(10**(-0.4*(Ms-Zp)))
eta=a**2/n
alpha=1
betha=-(SN)**2/g
gamma=-(SN)**2[n*A*(ron/g)**2+B*A/g+eta*B**2*A]
F=(-betha+sqrt(betha**2-4*alpha*gamma))/(2*alpha)
Ma=-2.5*log10(F)+ZpAirm
(magnitude limit at a given SN in an aperture w)
M=(Ma-Ca)
(total Magnitude of the object)
Description: given the seeing s, the pixel size p of LBC and the
aperture in arcsec w,
the ETC program computes the ratio r between the aperture and the
seeing. Then it computes the area A in pixel
for this aperture. The next step is to compute the background B in ADU
for the single pixel,
given the total exposure time t, the Magnitude of the Sky Ms, the Zero
point Zp at airmass=0.0. At the end one
computes the magnitude limit Ma at a given Signal to Noise ratio SN.
The magnitude of the sky Ms depends
on the Moon day (0,3,7,10,14) and the filter used. It is always
computed at airmass=0. It can be read from the
LBC Database.
The Zero Point for t seconds of exposure time, for a given airmass
and for a given filter is
ZpAirm=2.5*log10(t)+ZpAirma(t=1)
The zero point for 1 second of exposure time and for a given
airmass can be found in ZEROPNT.dat, where there are the zero
points for airmass=0.0,1.0,1.1,1.2,1.3,... and 3.0;
other values of airmass can be extrapolated.
The number of exposures n is computed dividing the Total Exposure Time
TET by the
Single Exposure Time SET for a single exposure. This parameter is
taken from the
right panel and it is the only parameter calculated by a cross talk of
the two
panels (TET and SET).
At the end one has the magnitude limit Ma for a given filter, moon,
exposure time,
airmass, seeing, aperture and Signal to Noise Ratio. These formulas
compute the
magnitude limit in an aperture w! If the object is greater than that
aperture,
the total magnitude of the object could be brighter. It is computed as
a simple
formula MagTot=Ma-Ca and displayed in the outputs of the ETC for the
TET panel.
####################################################################
Second case:
given the seeing s, the aperture for photometry w, the exposure time t
and
the magnitude of an object M, you can compute the Signal to Noise
ratio
SN in the given aperture. This result depends on the type of the
source:
star or galaxy (spiral or elliptical).
s=seeing (arcsec)
p=pixel size (arcsec/px)
t=total exposure time (second)
w=photometric aperture diameter (arcsec)
r=ratio between aperture w and seeing s (aperture in seeing units)
A=area (pixel)
M=total magnitude (AB mag)
Ma=magnitude at a given aperture (AB mag)
Ms=magnitude of the sky (AB mag/arcsec**2)
SN=Signal to Noise Ratio
F=total flux of the source in ADU
B=flux of the background (per pixel) in ADU
ZpAirm=magnitude zero point for a given Airmass
Zp=magnitude zero point for Airmass=0.0
Ca=correction aperture (for star, elliptical or spiral galaxy)
n=number of exposures
g=gain (e-/ADU)
a=flat field accuracy for a single exposure
ron=Read Out Noise of LBC (e-)
p=0.23
a=0.005
g=2.09
ron = 2.25
r=w/s
A=3.141592654*(s*r/(2*p))**2
B=t*(p**2)*(10**(-0.4*(Ms-Zp)))
eta=a**2/n
ZpAirm=2.5*log10(t)+ZpAirm(t=1)
Ma=M+Ca
F=t*10**(-0.4*(Mc-ZpAirm1))
SN=F/sqrt((F+B*A)/g+n*A*(ron/g)**2+eta*B**2*A)
Description: given the seeing s and the aperture w, first compute the
sky brightness B
and the area A using the above formulas. Then compute r, the ratio of
the aperture and seeing.
For a stellar source, find in the file totcorr_star.dat the row
corresponding to r=w/s;
the second column gives Ca, the correction for a given aperture.
For an elliptical galaxy, find in the file totcorr_ell.dat the row
corresponding to r=w/s;
For a spiral galaxy, the corresponding file is totcorr_spi.dat.
Search in the column corresponding to the seeing the correction Ca,
for a given aperture and
a given seeing. Then correct the input magnitude for Ca, compute the
flux F in ADU for the
given source and compute the Signal to Noise ratio SN. These formulas
compute the Signal to
Noise ratio in an aperture w. The term eta provides the contribution
of the flat field accuracy
to the Noise of a given exposure. It depends on the number of
exposures (a**2/n).
Warning: This is the reference formula for the ETC: the first and the
third cases of this panel
(TET) are derived inverting this formula. To enhance the Signal to
Noise Ratio it is possible
to act on the total exposure time t and/or on the number of exposures
n.
#############################################################################
Third case:
given the seeing s, the aperture for photometry w, the Signal to Noise
ratio SN and
the magnitude of an object M, you can compute the exposure time
required to reach SN
in the given aperture. This result depends on the type of the source:
star, elliptical
galaxy or spiral.
s=seeing (arcsec)
p=pixel size (arcsec/px)
t=total exposure time (second)
w=photometric aperture diameter (arcsec)
r=ratio between aperture w and seeing s (aperture in seeing units)
A=area (pixel)
M=total magnitude (AB mag)
Ma=magnitude at a given aperture (AB mag)
Ms=magnitude of the sky (AB mag/arcsec**2)
SN=Signal to Noise Ratio
F1=flux of the source in ADU for 1 second of exposure time
B1=flux of the background (per pixel) in ADU for 1 second of exposure
time
ZpAirm1=magnitude zero point for a given Airmass at 1 second of
exposure time
Zp1=magnitude zero point for Airmass=0.0 at 1 second of exposure time
Ca=correction aperture (for star, elliptical or spiral galaxy)
n=number of exposures
g=gain (e-/ADU)
a=flat field accuracy for a single exposure
ron=Read Out Noise of LBC (e-)
p=0.23
a=0.005
ron=2.25
g=2.09
r=w/s
A=3.141592654*(s*r/(2*p))**2
B1=(p**2)*(10**(-0.4*(Ms-Zp1)))
Ma=M+Ca
F1=10**(-0.4*(Mc-Zp1))
K1=(F1+A*B1)/g
alpha=F1**2-(a**2/n)*(SN)**2*B1**2*A
betha=-(SN)**2*K1
gamma=-(SN)**2*n*A*(ron/g)**2
t= (-betha+sqrt(betha**2-4*alpha*gamma))/(2*alpha)
Description: given the seeing s and the aperture w for photometry,
compute the ratio r between w and s.
Compute the area A of the aperture and the correction for a given
aperture Ca. Then correct the
input magnitude of the source for the Ca value, compute the flux of
the source F1 for an exposure time
of 1 second and B1 for the sky background. Then compute the total time
t needed to reach a given Signal
to Noise ratio SN in an aperture w.
Warning: The coefficient alpha must be a positive number. If it is
negative or null, no solution
can be reached. In this case it is useful to increase the Magnitude of
the source M or the number
of exposures n. In the same way, it is possible to decrease the given
Signal to Noise to reach
convergence in the calculations.
######################################################################
# SECOND PANEL (SINGLE EXPOSURE TIME)
######################################################################
These formulas link the Single Exposure Time (SET), the number of
exposures,
the Background and the Magnitude Saturation (Magnitude of a star that
saturates in a single exposure). Only one parameter is needed to
obtain the others.
----------------------
First Case:
Single Exposure Time is given
Given the single exposure time SET, compute the number of exposures n,
the background B
and the magnitude at saturation Msat for a single exposure.
s=seeing (arcsec)
p=pixel size (arcsec/px)
SET=single exposure time (second)
TET=total exposure time (second)
w=photometric aperture diameter (arcsec)
r=ratio between aperture w and seeing s (aperture in seeing units)
A=area (pixel)
Msat=magnitude at saturation (AB mag)
Ma=magnitude at a given aperture (AB mag)
Ms=magnitude of the sky (AB mag/arcsec**2)
SN=Signal to Noise Ratio
F=total flux of the source in ADU
B=flux of the background (per pixel) in ADU
ZpAirm1=magnitude zero point for a given Airmass at 1 second of
exposure time
Zp1=magnitude zero point for Airmass=0.0 at 1 second of exposure time
Ca=correction aperture (for star, elliptical or spiral galaxy)
n=number of exposures
betha=Moffat Profile Parameter
R0=scale length of Moffat profile
I(R)=intensity for a Moffat profile at a given radius R
Io=peak intensity for the Moffat profile I(R=0)
TF=total flux of Moffat profile
The Moffat profile is defined as follows:
betha=2.5
R0=s/(2*p)
I(R)=I0[1+(2**(1/betha)-1)*(R/R0)**2]**(-betha)
TF=Int_0^Infinity (2*pi*R*I(R)dR)
defining alpha=(2**(1/beta)-1)
we have
TF=I0*pi*(R0**2)/(alpha*(beta-1))
Io=alpha*(betha-1)/(pi*R0**2) is the maximum of the Moffat profile for
total flux TF=1
given all these relations, it is simple to compute the required
parameters.
n=TET/SET
B=SET*p**2*10**(-0.4*(Ms-Zp1))
I0=2**16-B
TF=I0*pi*(R0**2)/(alpha*(betha-1))
F1=TF/SET
Msat=-2.5*log10(F1)+Zp1
Description: the number of exposures n is the ratio between the Total
Exposure Time TET
and the Single Exposure Time SET. It should be an integer number, so
it is possible that
the product SET*n is substantially different from TET. In this case a
simple Warning is given.
Given the seeing of the observation s, and assuming a Moffat profile,
one computes the maximum
of the profile I0 for an object with total flux TF=1. Given the
Magnitude of the Sky Ms and
the Single Exposure Time SET, the Background B is derived. The
magnitude at saturation Msat is
computed for 65536 (2**16) ADU (full well capacity of a single pixel
for LBC). The maximum of
an image is the sum of the background and the peak of the source I0,
for an exposure time of SET.
Given the total flux TF required to saturate the frame for a Single
Exposure Time (SET), one can
compute the flux for 1 second F1 and then derive the Magnitude of
Saturation Msat. If the ADUs
are greater than 65536 (2**16) or equal, the image is saturated and an
Error message is given.
Warning: check that the Single Exposure Time (SET) is consistent with
the Total Exposure Time (TET).
It is not possible that SET is greater than TET. If TET is large,
verify that the combination of TET
and SET gives an adequate number of exposures n.
-----------------------------------
Second Case:
Number of Exposures is given
Given the number of exposures n, compute the Single Exposure Time SET,
the background B and
the magnitude at saturation Msat for a single exposure.
SET=single exposure time (second)
TET=total exposure time (second)
n=number of exposures
SET=TET/n
Description: the Single Exposure Time SET is derived dividing the
Total Exposure Time TET by the
number of exposures n. Then to derive the Background B for a Single
Exposure and the Magnitude
of Saturation Msat the formulas are the same of the First Case.
Warning: check that the number of exposures n is consistent with the
Total Exposure Time (TET).
n should be an integer number. If TET is large, verify that the
combination of TET and n gives
an adequate value for the Single Exposure Time SET.
-------------------------------------
Third Case:
Background is given
Given the Background B for a single exposure, compute the Single
Exposure Time SET, the number
of exposures n and the magnitude at saturation Msat for a single
exposure.
s=seeing (arcsec)
p=pixel size (arcsec/px)
SET=single exposure time (second)
TET=total exposure time (second)
w=photometric aperture diameter (arcsec)
r=ratio between aperture w and seeing s (aperture in seeing units)
A=area (pixel)
Msat=magnitude at saturation (AB mag)
Ma=magnitude at a given aperture (AB mag)
Ms=magnitude of the sky (AB mag/arcsec**2)
SN=Signal to Noise Ratio
F=total flux of the source in ADU
B=flux of the background (per pixel) in ADU
ZpAirm1=magnitude zero point for a given Airmass at 1 second of
exposure time
Zp1=magnitude zero point for Airmass=0.0 at 1 second of exposure time
Ca=correction aperture (for star, elliptical or spiral galaxy)
n=number of exposures
betha=Moffat Profile Parameter
R0=scale length of Moffat profile
I(R)=intensity for a Moffat profile at a given radius R
Io=peak intensity for a Moffat profile I(R=0)
TF=total flux of Moffat profile
SET=B/(p**2*10**(-0.4*(Ms-Zp1)))
n=TET/SET
I0=2**16-B
R0=s/(2*p)
TF=I0*pi*R0**2/(alpha*(betha-1))
F1=TF/SET
Msat=-2.5*log10(F1)+Zp1
Description: given the Background B for a single exposure, it is
possible to compute
the Single Exposure Time SET knowing the background for 1 second of
exposure time.
The number of exposures n is the ratio of TET and SET. The peak I0 of
a source at
the saturation level is derived using the background B. Given the
seeing of the observation s,
and assuming a Moffat profile, one computes from the maximum of the
profile I0 the total flux TF.
The magnitude at saturation Msat is computed for 65536 (2**16) ADU
(full well capacity of
a single pixel for LBC). Given the total flux TF required to saturate
the frame for a Single
Exposure Time (SET), one can compute the flux for 1 second F1 and then
derive the Magnitude
of Saturation Msat. If the ADUs are greater than 65536 (2**16) or
equal, the image is saturated
and an Error message is given.
Warning: it is not possible to enter a Background B greater or equal
to 65536 (2**16) ADU.
If TET is large, verify that the combination of TET and B gives an
adequate number of exposures n.
------------------------------------------
Fourth Case:
Magnitude at Saturation is given
Given the Magnitude at Saturation Msat for a single exposure, compute
the Single Exposure Time SET,
the number of exposures n and the Background B for a single exposure.
s=seeing (arcsec)
p=pixel size (arcsec/px)
SET=single exposure time (second)
TET=total exposure time (second)
w=photometric aperture diameter (arcsec)
r=ratio between aperture w and seeing s (aperture in seeing units)
A=area (pixel)
Msat=magnitude at saturation (AB mag)
Ma=magnitude at a given aperture (AB mag)
Ms=magnitude of the sky (AB mag/arcsec**2)
SN=Signal to Noise Ratio
F=total flux of the source in ADU
B=flux of the background (per pixel) in ADU
ZpAirm1=magnitude zero point for a given Airmass at 1 second of
exposure time
Zp1=magnitude zero point for Airmass=0.0 at 1 second of exposure time
Ca=correction aperture (for star, elliptical or spiral galaxy)
n=number of exposures
betha=Moffat Profile Parameter
R0=scale length of Moffat profile
I(R)=intensity for a Moffat profile at a given radius R
Io=peak intensity for a Moffat profile I(R=0)
B1=sky counts for 1 second of exposure time
F1=total flux for 1 second of exposure time
I1=peak intensity for 1 second of exposure time
TF=total flux of Moffat profile
B1=p**2*10**(-0.4*(Ms-Zp1))
F1=10**(-0.4*(Msat-ZpAirm1))
R0=s/(2*p)
I1=(F1*alpha*(betha-1))/(pi*R0**2)
SET=2**16/(B1+I1)
B=SET*p**2*10**(-0.4*(Ms-Zp1))
n=TET/SET
Description: given the Background B1 for 1 second of exposure and the
flux at saturation F1 for
1 second of exposure, it is possible to compute the peak I1 of a
source that saturates the CCD.
The Single Exposure Time SET is derived from the flux of the
background and the source for 1 second
of exposure time. The Background B for a single exposure is derived
using the Single Exposure Time SET
and the Magnitude of the Sky Ms. Then the number of exposures n is
derived referring to the
Total Exposure Time TET. If the ADUs are greater than 65536 (2**16) or
equal, the image is saturated.
Warning: if TET is large, verify that the combination of TET and Msat
gives an adequate number of exposures n.
9. INTERACTIVE POINTING
Inserting the RA & DEC coordinates for an observation it' s possible
to view an image of the sky (from GSC2 catalog) for the Blue and Red
Channel and the relative projection of the LBC-Chips (see following
fig.)
It's possible to offset and rotate directly the projection of the blue
and/or red channel interactively on the field of view. If you drag the
mouse on the position of a specific object the offset X and Y will
change istantaneoussly and if you reload the frame the RA and DEC will
be updated.
Acknowledgements
I wish to thank Faraday s.r.l. (www.faraday.it) for base GUI project
from which I took the first graphical appearance of the main
application.
I wish to thank also A.Grazian for ETC calculation formulas.
I wish to tank all the LBC TEAM for the many suggestions and requests
act to make the application better and better, in special way
A.Fontana, E. Giallongo and the Mythic one.
A special mention is dued to C. De Santis for his informatic support.
S.G.
Osservatorio Astronomico di Roma URL: http://www.mporzio.astro.it
Via Frascati, 33 e-mail: [email protected]
00040 Monte Porzio Catone, Italy [email protected]
Voice/Fax: ++39 06 9428641/++39 06 9447243 [email protected]
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