Navigation

• Home
• Acquisition software
• Cameras
• Checklist
• Contact
• Important notes
• Despeckling
• DOTgui
• Observing steps
• Observing strategy
• Observing Tools
• Preliminars
• Schedule
• Storing data
• Tuning Filters
• Troubleshooting

Observing checklist

This is a quick list you should go through at the start of every day and whenever you change targets. The reasons for all the steps are described in other wiki pages.

• Align the guider.

  • Go to the west rim. Use the manual control buttons to slowly move the telesope until the Calcium camera image shows the edge of the rim touching the center of the image (use the crosshair).
  • Click on “Rim1”.
  • Repeat this for the three other rim positions.
  • Click on “Calculate”, and if you are using the old IDL guider, ensure “Apply correction” is enabled.
  • Write the calculated offset in your log.

• Go to the target.

  • If it is an active region on the disk, enable rotation compensation.
  • If it is quiet sun or on or above the limb, disable rotaton compensation.
  • Fill in a descriptive name for the target.
  • Store the target.
  • Make a note of the coordinates (both SOHO and heliographic) and current time in your log.

• Set proper exposure times:

  • Tune Halpha, Barium and Calcium filters 1 Å into a wing.
  • Go to the target:
    • If your target is on or above the limb, go slightly below the limb so that the whole field of view of all the cameras is covers granulation.
    • If your target is a sunspot covering more than 50% of the field of view, go to a position closeby with only granulation.
  • Set the exposure time such that the peak of the histogram of each camera is around 60% or 70% of maximum intensity.
  • Never go above 15 ms, preferably stay below 10 ms, except for the Barium and Barium Continuum cameras.
  • Ensure the right hand tail of the histograms never touches the right end of the scale.
  • Red Continuum and Barium Continuum cameras need to be use the same exposure as Halpha and Barium, respectively.
    • If the continuum channels are then overexposed, reduce the exposure time of both the line and continuum channel.
  • Write the exposure times in your log.

• Find line centers (on the selected target location!):

  • Use the same position you used for exposure time calibration
  • IDL: plot, ha_init() and write down the “wing equality” value.
  • IDL: plot, ca_init() and write down the “wing equality” value.
  • IDL: plot, ha_init() and write down the “wing equality” value.
  • Update the script to use the wing equality values as the filter position origins.
  • Write the wing equality values in your log.

• Choose the correct prefilters:

  • When close to, on or above the limb, use the prominence setting for the Red Continuum and Barium Continuum filters.
  • When on the disk, use the continuum, setting for the Red Continuum and Barium Continuum filters.
  • Write the prefilter settings in your log.

• Check the focus:

  • Look at one camera image, preferably Calcium, disable the live view frame selection, and keep an eye on it while finding focus.
  • IDL: find_focus, 'scott', step=20 and check where the maximum is.
    • If the curve is very linear, the filter is in completely the wrong position. Tune Focus 100 microns to the direction of higher RMS values and repeat the scan.
    • If the curve is unclear (due to bad seeing), repeat the scan.
    • If a gaussian peak appears, tune Focus to the center of the peak.
  • IDL: find_focus, 'scott' and check where te maximum is again.
    • If the curve is unclear (due to bad seeing), repeat the scan.
    • If a gaussian peak appears, tune Focus to the center of the peak.
  • Ensure yourself that you indeed found the best possible focus by checking quality of the live camera image.
  • If the seeing is good, use the ?PD Focus program:
    • IDL: pd_focus
    • Click on the left or right image, and press + or - to increase or decrease the exposure time until the value in the top center of the focus program is close to 1.
    • Wait a few seconds, and ensure that the central sliders are close to the center.
    • If not, click the ‘++’, ‘+’, ‘-’ and ‘—’ buttons until they are more or less in the center.
  • Write the position of the Focus filter ni your log.

• Check the script:

  • When the seeing is good enough for despeckling:
    • When on the disk, take at least 100 images within each cadence cycle, use at least 20 images per burst when doing dopplergrams.
    • When on or above the limb, use 100 images per burst, don’t do dopplergrams or only use a 2-point dopplergram.
  • When the seeing is not good enough for despeckling:
    • You are mostly free to do whatever you like.
  • Ensure your cadence is less than or equal to 30 seconds.
  • Note your observing mode in your log.

• Make darks:

  • Skip this if you just arrived and the seeing is very good.
  • Use the guider to go to the dark position.
  • Change the FITS filename prefix to “dark”.
  • Run the script with only 1 repetition.
  • Write the time you made the dark in your log.

• Make flats:

  • Skip this if you just arrived and the seeing is very good.
  • In the PD Focus program, click on “Defocus”.
  • With the new guider:
    • Click on “Flat”.
    • If your target was near the limb, ensure no camera is overexposed. If it is, follow the steps for the IDL guider.
  • With the IDL guider:
    • Go back to the position you used to calibrate exposure and line centers. If there were pores or sunspots in the field of view, move slightly away until only granulation is visible.
  • Change the FITS filename prefix to “flat”.
  • Run the script with only 1 repetition.
  • In the PD Focus program, click on “Go back to focus”.
  • Write the time you made the flat in your log.

• Observe:

  • Go back to the stored target position in the guider.
  • Ensure the guider is tracking.
  • Check the cameras again to see you are on the desired target and exposure and focus is OK.
  • Change the FITS filename prefix to something short but descriptive of your target.
  • Quickly fill in the rest of the FITS fields as well as you can.
  • Start the script with a high number of repetitions.
  • Write the time in your log.

Now you can relax, but there will still be some things to do:

• Once every 10 minutes, check if everything is still OK.
• Every time you start the script to observe, go through the observing checklist.
• Once every hour, go through the focus, dark and flat checklists again. Making flats and darks shortly before or after the observation is VERY important!
• Think about whether or not you need to calibrate the line centers regularly if you are following a single target for a whole day.
• When you change your target, you have to go through the whole checklist again.
• Once a day, take an alignment measurement. Reasonable seeing is required for this (granulation clearly visible), hence do not wait too long after the observation :
  • Go to an area with quiet sun, preferably near the center.
  • Check the exposure times.
  • Try to focus as best as possible.
  • Change the FITS filename prefix to “align”.
  • Run the script with only 1 repetition.
  • If the seeing was bad during this run, repeat it a few times.
  • Write the time you made the alignment in your log.

If there are omissions in this checklist, edit the page and add them.