Va Parallax Obs/redux Notes

SSO 40inch CCD Observing and Reduction

For a general introduction to observing with the 40 inch, albeit not a totally uptodate
one (as of 1 Jul 96), see:

FIRST NIGHT CHECKLIST

Run teldisk first thing after starting cicada for the first time.
Set filename prefix and number.

Set readout region to region 2 and overscan to 32 columns. The image area should now appear thus:

              xval = 743
              yval = 226
            xwidth = 700
            ywidth = 700

Set pgain to 4.
Fix ETS coordinate display to show HA as minutes.
Start flats 15 minutes after sunset.
Calibrate coordinates.
Take trail and adjust rotation if necessary.
Set up SBIG.

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THE E.T.S. COORDINATE DISPLAY

The E.T.S. coordinate readout in the control room defaults to a display which shows HA as a fraction of an hour. To get it to display minutes, do the following on the ETS PC:

[Alt] x
C:\OBSERVER\PREVIOUS_USER> login
Enter Observer Identification: yale
C:\OBSERVER\YALE> startup
Choose "File" from the menu bar and select
Load Display File...
In the "Files" box, click on
DISPLAY.DSP (and then OK)

NB: The Unix PC no longer displays the HA at the start of the exposure, though it does still display the UT time. My method for recording the hour angles is to jot down the HA for a particular Civil Time (I do it on the minute) before the first exposure for a region (AFTER the centering is done, of course), and then just do the arithmetic thereafter. You can also estimate it by noting the HA at the start of the exp, then estimate it for the mid-time.

NB: In the event of a power interruption, the display in the dome may be lost. Doing a STARTUP as above should restore it.

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CALIBRATING THE COORDINATES

After you've centered a bright star as usual, use the coordinate readout PC to calibrate the coordinates as follows:

Choose "Configuration" from the menu bar and select Calibrate Pointing...

Enter the coords in standard MSSSO "2.3m" format, i.e.,

               HH MM SS.S DD MM SS.S

Click on Calibrate

NB: Pointing corrections are now in effect. When you move the telescope along one axis, you will see some change in the readout for the other axis. Pointing to the desired coordinates is now somewhat of an iterative process, e.g., slew RA, slew DEC, adjust RA, adjust DEC...

If you do the calibration from the almanac for 1996.5 (or whatever), then change to epoch 2000.0, just use 2000 coordinates if they are available. In this case you do not need to 'coco' to the current date.

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THE SBIG AUTOGUIDER

Setting up and checklist:

Check the parameters under the TRACK menu against the values on the sheet at the front of the SBIG manual in the control room.
Initialize the probe by driving it against the limits in the negative X and Y directions and then hitting reset for both X and Y.
Make sure the camera is mounted right side up on the telescope, and the x-axis is reasonably well aligned with RA.
Set the Newell guider focus to 13.0 using the black buttons on the box.
Check x,y, Probe calibration and focus

When you've finished calibrating the telescope coordinates, leave the bright star centered on the chip and try finding it with the SBIG. Set the SBIG gain down to 1x (in the CAMERA menu) and use FOCUS to start taking one-second exposure. Move the guide probe to x = 0, y = -10 (approximately)--you may need to move the probe somewhat to the west (+x) to aquire the star, since the chip region we're using is a bit west of center. Once you find it, use the focus knob on the SBIG camera mount to get the star as well focused as possible. Center the star on the SBIG chip using the probe and make a note of the offset in x and (mostly) y (around -10 mms) for future reference when searching for guide stars. Play with probe buttons a bit to get a sense of which directions they move the star. Play with the telescope guide buttons as well to verify the orientation of the SBIG chip.

Autoguiding: 10th or 11th mag guide stars seem to work well at around 5 seconds. Much longer exposures are better if the seeing is not great, otherwise the sbig chases the seeing. The guide probe focus can vary quite a lot across the field--it's worth taking some care with the camera focuser to get the guide stars as round as possible.

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BIAS, TRAIL AND FLATS

I (mcb) like to avoid saving useless stuff to disk unnecessarily by taking these types of frames in "manual mode"--rather than using the EXPOSE AND SAVE macro, use the following macro sequence:

OPEN SHUTTER (reply with exposure time)
READOUT CCD

If it's a keeper (e.g., trail is parallel to edge, or SURVEY AND PRINT shows the flat field to have good counts)

WRITE AS NEXT TO DISK AND SUN (reply with header info)

Trail Hints: Position a reasonably bright star in the NE or SE corner of the frame-- putting it near the N or S edge helps tell if the trail is straight. Once it's in position, write down the coordinates-- that way you can go right back to it if you need a couple tries. A 40 sec exposure will trail an equator star all the way across the frame, provided you move briskly into the dome to turn off the drive.

Flat Hints: You must begin within 15 minutes after sunset. With the drive ON start taking 1 sec exposures until the counts move into a good range (40k-60k), then start adjusting the exposures accordingly, and move on to other filters before the counts get too low and stars become a problem. It is best to start with the bluest filter and step redward, but note that the R and I filters are used almost exclusively (except for a couple of regions and nights of photometry), and so are more important than V or B. Always move the telescope between each exposure. It's probably also a good idea to flush the ccd before each new exposure, since OPEN SHUTTER will not do this automatically the way EXPOSE AND SAVE does. In the morning, start with long I exposures and work your way to V--quit when the exposures go below 1 secs. When you have enough flats to be able to pick and choose a bit more, make a point of trying for other flats with better counts (and NO stars!) and flats with longer exposures.

You may also use the EXPOSE NO SAVE (macro 8) then write to SUN; this has advantage of reminding you which filter is in, and it does flush the CCD.

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PRECESSING COORDINATES

coco
<- i 5 2000.0

(to set input to J2000.0 or i 4 1950 for B1950.0)

<- o 5 1997.6

(for example)

<- HH MM SS DD MM SS
<- e

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CONVERSION TO .DST

         SYNTAX: cfits2dst frame(s).fits
          USAGE: Converts Cicada-generated fits frames
                 to dst--wildcards may be used to specify
                 multiple fits frames.
       EXAMPLES: fits2dst pbr0100.fits
                 fits2dst pbr010[1-9].fits
                 fits2dst *.fits

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TO CHECK IMAGE QUALITY AND SEEING:

rm cu* ce* [or rmc] (to remove old cursor.dat & center.dat)
cpos baseNNN (where NNN is frame number)

put cursor on star of interest
hit spacebar to mark
hit q to quit (reply y in xterm)
docont frame x y (x and y coords from cpos)
centers

Hit RETURN for various defaults. Reply y when prompted to change parameters. Use 10 for new width and min and max values from docont output to set new range. Eyeball the width from the image profile. FWHM in arcsecs is approximately the width in pixels.

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MAKING MEAN FLATS

mistat flat_fields

eg mistat pbx201.dst pbx202.dst pbx205.dst ...

lpr mistat.log
choose flats with good mean counts (30-50k), not saturated, and well-exposed (> 1 secs).
clean flat_field (if necessary)

Figdisp needs to be running at 700x700 for cleaning. If it's not already, kill it by hitting F9 with the cursor in the display, and restart it with
figdisp -bm 700x700

create mean flat

SYNTAX: addflat flat1.dst [flat2.dst flat3.dst ...]
 USAGE: Creates a mean flat using any number of flats.
        Output is to the file 'meanflat.dst', which 
        should always be renamed appropriately.

clip (to remove extremes - checkwith 'ISTAT')

             im meanflat
             lo 0.2
             hi 2.0
             ou meanflat

mv meanflat newname

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FLAT FIELDING FRAMES

Create flat fielded frames with mflat.

SYNTAX: mflat meanflat frame(s)
USAGE: flat-fields specified frames using specified mean flat
EXAMPLE:  mflat vflat.dst pct10*.dst pct22[34].dst

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BACKING UP .DST FRAMES

We are now using tar instead of ddt for backing up raw and flat-fielded .DST frames. Load an exabyte in the drive and do the following from within the data directory:

Allocate drive and find the end of medium:
1. allocate ex0
2. mt eom (Skip this ONLY when you're writing the first archive at the beginning of the tape.)
Create the tape archive:
1. tar cvf $EX0 frames (use wildcard for frames, e.g., pbi2*.dst to backup all the pbi 200's)
Backspace to beginning of archive and verify it, writing a listing to a log file:
1. mt nbsf
2. tar tvf $EXO >> xbpbi.log (or xbfpbi.log for flat-fielded frames)
Rewind, unload and deallocate:
1. mt rewoffl
2. deallocate ex0

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PROBLEMS AND FIXES

RECOVERING FROM ACCIDENTALLY SKIPPED FRAME 

     1)  Fix log book
              whiteout frame number(s) and leave note in comment area.
     2)  Fix header info in .DST frame(s)
              exam baseNNN...  (to view the whole header)  
              delobj

                   reply baseNNN.fits.comment

              crobj
                   
                   reply baseNNN.fits.comment
                   reply char

              let
            
                   reply "BASE NNN FILTER EXPOSURE"

              exam baseNNN...  (to verify the change)

     3)  Fix observing log:

              cp /ccd/obslog.lis .  (yes to overwrite)
              vi obslog.lis

                   edit appropriate lines

SBIG

Guide star goes walkies

It should be rightside up - label readable

Another thing to check is whether the cable from the sbig is physically connected to the drive corrector--it's a multi-pin cable low to the floor around the back of the the dome console, that says something like "from the telescope". I have had the sbig go along merrily opening and closing relays to no avail. Telltale sign is that the sbig SEEMS to be guiding, but the star shows signs of accumulative drift.

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SSO 40inch CCD Observing and Reduction

For a general introduction to observing with the 40 inch, albeit not a totally uptodate
one (as of 1 Jul 96), see:

MSSSO 40-inch UserGuide

STARTING UP ON THE SUN

FIRST NIGHT CHECKLIST

THE E.T.S. COORDINATE DISPLAY

[Alt] x
C:\OBSERVER\PREVIOUS_USER> login
Enter Observer Identification: yale
C:\OBSERVER\YALE> startup
Choose "File" from the menu bar and select
Load Display File...
In the "Files" box, click on
DISPLAY.DSP (and then OK)

CALIBRATING THE COORDINATES

THE SBIG AUTOGUIDER

BIAS, TRAIL AND FLATS

OPEN SHUTTER (reply with exposure time)
READOUT CCD

WRITE AS NEXT TO DISK AND SUN (reply with header info)

PRECESSING COORDINATES

coco
<- i 5 2000.0

<- o 5 1997.6

<- HH MM SS DD MM SS
<- e

CONVERSION TO .DST

SYNTAX: cfits2dst frame(s).fits USAGE: Converts Cicada-generated fits frames to dst--wildcards may be used to specify multiple fits frames. EXAMPLES: fits2dst pbr0100.fits fits2dst pbr010[1-9].fits fits2dst *.fits

TO CHECK IMAGE QUALITY AND SEEING:

MAKING MEAN FLATS

mistat flat_fields

lpr mistat.log
choose flats with good mean counts (30-50k), not saturated, and well-exposed (> 1 secs).
clean flat_field (if necessary)

FLAT FIELDING FRAMES

Create flat fielded frames with mflat.
SYNTAX: mflat meanflat frame(s) USAGE: flat-fields specified frames using specified mean flat EXAMPLE: mflat vflat.dst pct10*.dst pct22[34].dst

BACKING UP .DST FRAMES

PROBLEMS AND FIXES

SSO 40inch CCD Observing and Reduction

For a general introduction to observing with the 40 inch, albeit not a totally uptodate one (as of 1 Jul 96), see:

[Alt] x C:\OBSERVER\PREVIOUS_USER> login Enter Observer Identification: yale C:\OBSERVER\YALE> startup Choose "File" from the menu bar and select Load Display File... In the "Files" box, click on DISPLAY.DSP (and then OK)

OPEN SHUTTER (reply with exposure time) READOUT CCD

WRITE AS NEXT TO DISK AND SUN (reply with header info)

coco <- i 5 2000.0

<- o 5 1997.6

<- HH MM SS DD MM SS <- e

SYNTAX: cfits2dst frame(s).fits USAGE: Converts Cicada-generated fits frames to dst--wildcards may be used to specify multiple fits frames. EXAMPLES: fits2dst pbr0100.fits fits2dst pbr010[1-9].fits fits2dst *.fits

mistat flat_fields

lpr mistat.log choose flats with good mean counts (30-50k), not saturated, and well-exposed (> 1 secs). clean flat_field (if necessary)

Create flat fielded frames with mflat. SYNTAX: mflat meanflat frame(s) USAGE: flat-fields specified frames using specified mean flat EXAMPLE: mflat vflat.dst pct10*.dst pct22[34].dst

For a general introduction to observing with the 40 inch, albeit not a totally uptodate
one (as of 1 Jul 96), see:

[Alt] x
C:\OBSERVER\PREVIOUS_USER> login
Enter Observer Identification: yale
C:\OBSERVER\YALE> startup
Choose "File" from the menu bar and select
Load Display File...
In the "Files" box, click on
DISPLAY.DSP (and then OK)

OPEN SHUTTER (reply with exposure time)
READOUT CCD

coco
<- i 5 2000.0

<- HH MM SS DD MM SS
<- e

lpr mistat.log
choose flats with good mean counts (30-50k), not saturated, and well-exposed (> 1 secs).
clean flat_field (if necessary)

Create flat fielded frames with mflat.
SYNTAX: mflat meanflat frame(s) USAGE: flat-fields specified frames using specified mean flat EXAMPLE: mflat vflat.dst pct10*.dst pct22[34].dst