PRIMUS IMACS instructions

From NYU CCPP Wiki

This is a page about the PRIMUS project. See also PRIMUS observing checklist.

Afternoon alignment images:

Flat field screen IN. We find that no lamps are necessary, however. 1 second images get enough ambient light to see the boxes easily (2000 counts per pixel).

Take for every mask. 1 image per mask.

Arcs:

Flat field screen IN. Both He lamps on. Prism in. Spectroscopic filter. 1 second exposure time. 1 image per mask is fine.

icbox:

icbox takes direct images of the mask and builds files that contain the subraster information and the alignment box locations.

In the data directory, 'epar icbox'. Set 'mask' equal to the CCD data file containing the direct image. Set 'output' equal to your desired name, likely the mask name. It will append .align and .sub. Set 'sz' to the size of the alignment boxes (25 pixels). Set 'subrast' to the size of the subraster box (200 pixels). :g will then run the script (or :q to quit). First, reset the stretch if necessary: 'd' then type min and max counts. Then, put cursor on the boxes and hit space. Hit 'q' to go to the next frame.

When done, start again with 'epar icbox'

Dome flats (used for pixel-to-pixel variations):

No slitmask, no prism or disperser. If using ambient light (preferred) then 20 seconds in R, 10 seconds in I, and 40 seconds in V. If using the 'Ql' lamp with the flat field screen IN, then 4 seconds in B and 1 second in V will work. Do not use for R or I; it will saturate.

Take 10-20 bias frames as well.

ialign:

This does a large move to put the stars in the icbox regions in the .align file.

Settings are mask = afternoon CCD frame filename field = current CCD frame filename align_fi = .align filename sz = 25 # box size query0 = yes # So you can reject bad stars inter = no # So you don't have to see the x/y plot # If you end up in the plot, hit 'q' to quit out of it # and 'x' or 'y' to see the plots.

ialign will then page through the 16 box regions and suggest a star match. You will need to hit 'd' to set the stretch, then enter the min and max counts. 'a' to accept the suggested star match; 'm' to force a match onto the cursor.

When done, answer the questions to send the command to TCS. Record the motions in the log.

ifalign:

This does a fine scale move within the box. Settings:

mask = current CCD frame filename align_fi = .align filename inter = no # no residual plot sz = 25 # box size fwhm = 5 # For the star FWHM query0 = yes # To allow you to delete bad stars

Then use 'q' to step through the stars. Keep track of one's you want to reject (or look at the list at the end).

When done, answer the questions to send the command to TCS *if* the motions are large enough to matter. Rotation < 0.005 deg and RA/Dec less than 0.1 arcsec is fine. Record the motions in the log.

subraster:

To select subraster mode for an image read-out, change 'exptype' from 'full' to 'subraster'. A window will pop up. Hit 'file' and then select the appropriate .sub file. Then hit 'load', 'apply', and 'done'. Important: 'savemode' must be kept as 'full'.

nod & shuffle:

To select N&S, change 'exptype' from 'object' to 'nod & shuffle'. A window will appear. Enter the shuffle amount (2.0 arcseconds = 10 pixels), the RA and Dec nod amount, the dwell time (60 seconds), and the number of cycles (each A & B counts as 1 total).