This is a guidebook for Stony Brook users of ANDICAM images. It requires access to the raid array on osiris, and some knowledge of IDL. The IDL procedures are located in /home/fwalter/LIBS. This directory must be in the IDL_PATH variable in your .cshrc file.
Images are taken by service observers. The data are downloaded to Yale each morning, where the data are archived. The optical (CCD) images are processed, by trimming the images, subtracting the bias, and dividing by the flat fields. The infrared images are rebinned to a manageable scale, but are otherwise archived raw. The images are placed on the SMARTS ftp site after processing. We download the data from there.
We utilize both the optical (CCD) and infra-red (IR) channels.
The images themselves are stored on the raid array on osiris. The catalog of images is maintained in a pair of IDL databases, one for each channel. For manageability, a new database is created for each observing year. SMARTS began operations in 2003. Note that the observing year generally, but not always, runs from February through January. After downloading the images, we update the databases.
In order to access the databases, you must have the following line in your
In order to access the IDL software, you must have a line in your .cshrc
file that looks like the following:
setenv IDL_PATH +/usr/local/rsi/idl_5.3/local_pro:+/home/fwalter/ASTROLIB:+/home/fwalter/LIBS:+/usr/local/rsi/idl_5.3/lib:
The databases are named s13_yyyy and s13ir_yyyy, for the optical and near-infrared data, respectively. yyyy is the year (e.g., 2006)
While you can in principle query the databases using any IDL databasing routines, most routine queries are handled through the software described below.
There are two primary ways of querying the databases.
GET_ANDICAM lists only the dates (in yymmdd format) that the observation was made: it doesn't provide any other information. For more you'll need to run S13DB_TARGET (see below).
GET_ANDICAM can be run with a number of optional keyword parameters. Type GET_ANDICAM,/help for a full listing. The most useful keywords are:
For example, to find out when we got near-IR images of the polar QS Tel in 2005, you would type GET_ANDICAM,'QS Tel',/y2005,/ir
Note that GET_ANDICAM can also be used to extract data from the database. The full list of option is:
* GET_ANDICAM - get ANDICAM data * calling sequence: GET_ANDICAM,target,date,im,filt,med * TARGET: name of target, as recorded in s13_* database * DATE: date of data to be grabbed. * If omitted, a list of dates is returned. EXPT: returned exposure times * IM: a 1024x1024xn array containing all the images for this date * FILT: list of filters corresponsing to the n images * MED: the median-filtered image, if only one filter exists OR * keyword FILTER is specified * * KEYWORDS * ALL: set to return all data when both ccd and rccd files exist * DB: data base to be searched, def=s13_2003 * FILTER: set to one of U,B,V,R,I to return image(s) in only one band * IR set to read IR database, def= CCD * JD: output Julian date of start of obs * MARK: filter names for interactive shifting, if needed * MERGE: set to merge CCd images, or sky-subtract and merge IR images * MSC: upper TV scaling parameter, def=10 * NOBINDOWN: if not set, rebin to 512x512 * PROPID: set to search on propid rather than target name * RAW: set to return unprocessed data when both ccd and rccd files exist * SAVE: set to save merged image in .fits file * SET: set number in multiobservational set, def=1 * THISDIR: use files in this directory rather than database * TIMES: output JD hours at start of observation * TV: set to display median or reddest image * Y200x: search database for year 200x; def=this year. * YSTART: starting Y pixel, def=12, height=952
For example, to get the details of the V1118 Ori observations on Jan 16 2006, you would type S13DB_TARGET,'V1118 Ori','060116'. The output is
Catalog of SMARTS ANDICAM Observations 2006 ---------------------------------------------------- civil Date Time filter Exposur air date time mass (sec) ---------------------------------------------------- 060116 2006-01-17 03:01:39 B 66.00 1.110 060116 2006-01-17 03:03:35 B 66.00 1.110 060116 2006-01-17 03:05:30 B 66.00 1.110 060116 2006-01-17 03:07:45 V 23.00 1.110 060116 2006-01-17 03:08:58 V 23.00 1.110 060116 2006-01-17 03:10:10 V 23.00 1.110 060116 2006-01-17 03:11:38 R 18.00 1.110 060116 2006-01-17 03:12:45 R 18.00 1.110 060116 2006-01-17 03:14:16 I 10.00 1.120 060116 2006-01-17 03:15:15 I 10.00 1.120The Civil date is the date at the start of the night in yymmdd format. The Date and Time are in UT. In this example, there were 10 individual exposures in the 4 filters.
Catalog of SMARTS ANDICAM Observations 2006 ----------------------------------------------------------- civil Proposal Object filter Exposur date ID time (sec) ----------------------------------------------------------- 060116 SUNY-03B-0001 BL Hyi B 100.00 060116 SUNY-03B-0001 BL Hyi V 100.00 060116 SUNY-03B-0001 BL Hyi I 100.00 060116 SUNY-03B-0002 V1118 Ori B 66.00 060116 SUNY-03B-0002 V1118 Ori B 66.00 060116 SUNY-03B-0002 V1118 Ori B 66.00 060116 SUNY-03B-0002 V1118 Ori V 23.00 060116 SUNY-03B-0002 V1118 Ori V 23.00 060116 SUNY-03B-0002 V1118 Ori V 23.00 060116 SUNY-03B-0002 V1118 Ori R 18.00 060116 SUNY-03B-0002 V1118 Ori R 18.00 060116 SUNY-03B-0002 V1118 Ori I 10.00 060116 SUNY-03B-0002 V1118 Ori I 10.00 060116 SUNY-04A-0011 Nova LMC 2005 V 90.00 060116 SUNY-04A-0011 Nova LMC 2005 R 30.00 060116 SUNY-04A-0011 Nova LMC 2005 I 90.00 060116 SUNY-04A-0011 Nova LMC 2005 B 90.00 060116 SUNY-04B-0012 V1647 Ori I 101.00 060116 SUNY-04B-0012 V1647 Ori I 101.00 060116 SUNY-04B-0012 V1647 Ori I 101.00 060116 SUNY-04B-0012 V1647 Ori R 101.00 060116 SUNY-04B-0012 V1647 Ori R 101.00 060116 SUNY-04B-0012 V1647 Ori R 101.00 060116 SUNY-04B-0012 V1647 Ori V 197.00 060116 SUNY-04B-0012 V1647 Ori V 197.00 060116 SUNY-04B-0012 V1647 Ori V 197.00Four of our targets were observed on that night.
The formal ANDICAM observing logs are maintained at this site. These logs are not easily searchable, and some are missing, but they are a good source of information. Data that we have not downloaded will not be listed in our database.
If we had an unchanging sky, so that the atmospheric transparency was constant,this would be enough. But the sky varies. Clouds drift over. Seeing changes. Therefore, we also do photometry on a sample of other stars in the field. These are the comparison stars. The assumption behind relative photometry is that the ensemble average of the brightness of the other stars does not change. Any variations we see must be due to the atmosphere. This will affect out targets and all the other stars in the field equally. We can therefore use the ratio of the counts in our target to the counts in the comparison stars to study the true variations in our target. The ratio of counts is the difference of instrumental magnitudes.
Generally the .compos file will exist. You will need to know where the target is, because all positions are measured relative to that. The target can be identified on its finding chart.
The usual procedure is to type
ANDICAM_PHOT will pause and ask you to mark the target. Move the cursor to the target position and click the left mouse button. After that, the program should continue autonomously.
If you click the right mouse button additional information about the target will be written to the terminal, and the radial counts plot will be shown in another window. This additional data will look like this:
Filter = V ecor= 1.14673 Centroid at 474.940 558.464 V: Source: Max = 1204.41 Net = 13085.13 Background: Median = 335.97 Mean = 336.03 +/- 10.95 Area= 876 Gaussian fit: Source: peak = 812.17 +/- 16.41 counts; Sigma = 1.47 +/- 0.02 pix Net in image = 11783.86 Net in fit = 11078.55 Background = 336.71 +/- 0.46The most important values are:
When done, the output is sent to the terminal. It will look like this (the lines may be much longer and wrap around):
060112 B 53748.732 5.568 -5.692 0.019 -4.372 0.061 -5.824 0.017 -5.213 0.029 -5.394 0.025 060112 V 53748.734 5.614 -5.475 0.020 -4.329 0.055 -6.271 0.010 -5.527 0.019 -5.911 0.014 060112 I 53748.736 5.662 -5.651 0.015 -4.127 0.058 -6.296 0.009 -5.564 0.016 -6.023 0.011
There will be one line for every image measured. Each line consists of the following: the civil date, the filter, the Julian date (-2400000), the starting time in hours UT (which give more accuracy than the Julian date), and then pairs of instrumental magnitudes and errors. The first pair is the target; subsequent pairs are the comparison stars.
You should cut and past the output lines into a text file called target.mag (where "target" is the name of the target. You should also check the IMEXAM output, and write the Source: Max and Sigma values on a commented line (one starting with a semi-colon).
ANDICAM_PHOT has lots of other options that you should not have to invoke. The online help file is:
* ANDICAM_PHOT - ANDICAM Photometry: combines get_andicam and apphot * calling sequence: ANDICAM_PHOT,target,date * TARGET,DATE: required * * KEYWORDS: * COMPOS: file containing comparison star positions * IMAGE: optional output image array * LOUD: set for full apphot output * MARKALL: set to mark stars in each image * MARKTARGET: set to mark target in each image * MERGE: set to merge multiple images in same filter * PDM: set to compute and print differential magnitudes * RADIUS: apphot radius, def=9 * RADT: apphot radius for target, def=RAD * RANGE: plot range, def=100 * SET: data set to read * SHIFT: set to shift images prior to merging * STARTFILT: filter to start with * TARGET: name of target, if defined for automatic extractions * USEIMAGE: name of input image - bypasses database * ZOUT: output magnitude differences
By default, ANDICAM_IR tries to shift and add the images autonomously (the /MERGE keyword). It often fails: the consequence is images with doubled or trailed stars. To help the program out, use the keyword IDT=2. The procedure will then display each image, and you will click on a bright object (it need not be the target, but it must be in all images in a given filter). The software will then center up on that. Note that these images will be rotated by 90 degrees, and will not look like the finding chart.
After the merger process, the properly rotated, shifted-and-added image is displayed. Click (L or R, as desired) on the target. Be aware that in many cases the target is very faint in the IR bands.
Things to note: in the IR images the non-linear response sets in at about 4000 counts. Please note if the Source: Max: value exceeds this. Also, in the IR images the sky subtraction should result in a background very close to zero. Please note if this is not the case.
The full range of options are:
* ANDICAM_IR - ANDICAM IR Photometry: combines get_andicam and apphot * calling sequence: ANDICAM_IR,target,date,zout,image * TARGET,DATE: required * ZOUT: output magnitude differences * IMAGE: optional output image array * * KEYWORDS: * COMPOS: file containing comparison star positions * IDTARG: set to mark target in individual images in merge_ir * LOUD: set for full apphot output * MARKCOMP: set to mark target and comps in all images * MARKT: set to mark target in all summed images (apphot) * MED: set to return median images, def=sum * MERGE: set to merge multiple images in same filter (def) * RADIUS: apphot radius, def=9 * RADT: apphot radius for target, def=RAD * RANGE: plot range, def=10 * TARGET: name of target, if defined for automatic extractions
Raw CCD data (prefix ccd) are not generally available.
The only calibration remaining is the photometric calibration. This is not normally important, as the data are generally used for relative photometry. However, on photometric nights 1 or 2 photometric standard stars are observed. These do not yield a full photometric solution, but can be used to establish the photometric zero-point to within probably 10%.
To use these, you must download CCD standard star observations to /raid1/DATA/SMARTS/1.3m/CCDSTAND/processed
Then use ANDICAM_CAL to determine the zero point on a particular night.
* ANDICAM_CAL: do crude absolute calibration for ANDICAM * calling sequence: ANDICAM_CAL,date,meandm * DATE: 6 digit civil date * MEANDM: nx5 array of delta mags, n sets, UBVRI * * KEYWORDS * CHECK: check what fields exist, do not reduce * NEW: set to re-reduce calibration fields * RADIUS: aperture radus, def=13 pix
Use ANDICAM_ZP to apply zero-point correction to magnitude data file. mean magnitudes amd standard deviations are printed, and returned in output MMAG and SMAG arrays (nstars x nfilters).
* ANDICAM_ZP: apply zero point correction to ANDICAM photometry * Calling sequence: ANDICAM_ZPfile,mmag,smag,filt * FILE: name of input magnitude file * MMAG: mean magnitudes of all stars * SMAG: stddev of all stars' * FILT: filter names
The user must do the flat fielding, dark and sky subtraction, and shifting-and-adding. These tasks are built into the ANDICAM_IR procedure. For this to work correctly, you must make and use the most recent flat and dark frames. To make them from the raw calibration data, use IRFLATS.
* IRFLATS - make ANDICAM IR flats * calling sequence: IRFLATS,dates * DATES: list of dates to process (string) * * KEYWORDS: * MON: set to yymm to process entire month /
To find nearest IR flats on disk, use GET_NEAREST_IRCAL()* GET_NEAREST_IRCAL - find nearest ANDICAM IR flat files * calling sequence: FILES=GET_NEAREST_IRCAL,date,files * DATE: date in question * FILES: output list of cal files
To do a crude photometric calibration, use ANDICAM_IRCAL
VIII. Examining the Light CurveUse RD_MAGDAT* RD_MAGDAT - read ANDICAM extracted photometry file * calling sequence: procname,file,jd,dm * FILE: def=mag.dat * * KEYWORDS * ABSOLUTE: set for absolute photometry (requires *.cmpmag or *.magcor file) * COMP: comp stars to compare: 2-element vector or mean * IGNORE: comparison star numbers to ignore (1-N) * JD: Julian dates, 2003, 2004, range(2),min, -max * LABEL: label stars * STARS: select comp stars, def=all. Supercedes IGNORE * STOUT: named structure for output variables * NOCONNECT: if not set, dots are connected * OPTREND: set to overplot linear trend * PLT: set to plot delta mag * PMM: set to use mean comparison magnitude (OPMM to overplot) * PWM: set to use weighted mean comparison magnitude (OPWM "" )