2.3 Telescope Zero-Point (CSET)

• Ask the operator to point to a bright star for the zero-point
• In RetroCam-Control window set:
  • Exptime = 3
  • Readmode = Double
  • ObjType = test or astro
  • Filter = Yc
  • Loops = 1
  • Object = pointing
• Take an image with Go.
• In the QuickLook window click on the center of the bright star.
• On the right of the same window, click on the Center button.
• In Telescope control window click on the 0,0 button.
  This will move telescope so the bright star will be at the field center.
• Take another image to confirm.
• Ask the operator to do the 'CSET'.

2.4 Telescope Focus

• Same focus value will work for Y and H filters, while an offset of -100 units is needed for J (new focus system).
• If the focus is fairly good, ask te operator to start a sequence, take a single 10sec image, and wait for the operator to change the focus value. The sequence should be taken from lower to higher values of the focus, increasing by 10 units per step. If the seeing is very good, you may want to decrease the focus step to 5 or 3 units to get the best image quality.
  • Exptime = 10
  • Filter = Yc
  • Loops = 1
  • ObjType = test or astro
  • Object = Focus,
• In the iraf window, type
  retrocam> disi 'image_number' 1
  For example if the image just taken is irr_00015_0001.fits, type: 'disi 15 1'.
• This will run 'display' and 'imexam' (see Section 4 below) on the image, so you can use the commands 'r' and 'e' to evaluate the image quality and decide which is the best focus.
• Tell the operator what the best focus was so that he does an fset.

3. Observing

 Tip:It would be really helpful if any non-useful image 
(focus tests for example, acquisition images, or any other test)
 are taken with "unusual" exposures as: 9,19,29,... etc.
 Those images should be ignored by the pipeline, but in case they
 enter into the process for any reason, it is much easier to catch
the problem when the exposures are this type.

3.1 Supernovae

• Check the current list of target list for RetroCam.
• In the RetroCam task bar click on File and Open ObjectList. This will bring up a window where you can select the ObjectList you want to open.
• Select the file csp_13_14.objects and click Open.
• The current list of SNe being followed is displayed.
• You can use the buttons to Add, Edit, or Remove an object.
• The system will offer to save any changes before you upload a different ObjectList.
• The Preview button shows the situation of the selected target in the Airmass and the Skymap windows without having to point the telescope to the object.
• The setObject button will send the target coordinates to the Telescope control window.
• In the Telescope control window use the Send button to send the coordinates to the TCS.
• Ask the telescope operator to slew to the target.
• Take a short exposure to check pointing and focus. In the RetroCam-Control window set:
  • Filter = Yc or Jo
  • Exptime = 10 or 20s, depending on source brightness
  • Loop = 1
  • ObjType = astro
  • Object = this field will be automatically read from the ObjectList.
• Take a test image by clicking on Go.
• Check that the field is the one shown in the finding chart.
• If you need to correct the pointing, use the dx and dy offsets and the directions panel in the Telescope Control window. These offsets will be applied in arcseconds; remember that the image scale is 0.201" per pixel.
• The upper-left (NE) quadrant should be avoided because it contains several dead spots.
• Also check that the SN and some of the field stars will end up having decent counts and not saturating with the exposure time to be used.
• Reset the Filename counter to the value previous to the test, and set Exptime, Loops, and Dither as desired. To reset the Filename counter you need to go to the RetroCam menu on the top task bar and select Camera and then File Number. Be aware that this will override any existing images starting with the number you set there.
• To define a Macro, press Dither and select the options of Dither-Step, Dither-Pattern, and Guider. You can either select Guider = auto or Guider = none and go without guiding. In the latter case, use loops = 1 and do as many dither sequences as needed to get the desired total exposure time.
• Leave ReadMode as Double for all the observations.
• Start a dither sequence by pressing Execute in the RetroCam-Control window.
• Repeat this procedure with every requested filter.
• If the field contains extended objects (larger than the selected dither step) you need to offset and get a sky sequence for each observed filter. Normally offseting for 120" in any direction is fine. Use dither = 5 and loop = 1 for sky, no matters what you are using for the target. Do not add anything to the 'Object' field in the RetroCam control window, leave the target's name there as it is. See Section 5 below.
• Check the background level, especially for H filter. If it grows too high (say, over 15000 counts) you need to reduce the exposure time on the individual images.
• Also remember to apply the focus offset when you change from/to J.
• Make use of the quick-processing scripts described in Section 4 below to check the quality of the data and perform quick photometry.

3.2 Standard Stars

• If the night is photometric, observe at least 3 or 4 Persson Standard stars (7-8 is desirable).
• In the File top bar menu select Open ObjectList.
• In the window that opens, select the file CSP.persson.objects and click Open.
• The list of Persson standards used by CSP is displayed.
• The same list is also available from here.
• Make sure the standard stars you observe in one night cover a wide airmass range between 1 and 2.5.
• Select an STD. from the object list, then press setObject and finally, on the Telescope Control window, click on Send. Tell the operator to slew the telescope.
• In the RetroCam-Control window select:
  • Exptime = 5
  • Readmode = Double
  • ObjType = astro
  • Loops = 1
  • Object = will be read automatically from the ObjectList
• Take a test exposure with Go and check the field and exposure time. Make sure the standard is not saturated. If so, ask the telescope operator to defocus the telescope a bit.
• You may need to move the star off the quadrant divisions. If so, in Telescope Control set dx and dy to something like 50 and move diagonally in the chip. This offset should be now smaller. Try with smaller offsets and cross-check.
• Avoid the upper-left (NE) quadrant. It cointains spots of dead pixels.
• In the RetroCam-Control window select the macro by clicking on the Dither button. Then select:
  • Dither-Step = 15'' (or leave it as 5'' which is also fine).
  • Dither-Pattern = rot-5
  • Guider = none
• Launch a dither sequence by clicking on the Execute button.
• Change filter and repeat the previous step until you have done Yc, Jo and Hc.
• Remember to apply the focus offset when changing from Y-H to J.