AO imaging of Beta Pictoris

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Beta Pic Observation

Schedule

From Sunset to the time Beta Pic reaches elevation limit (15 deg ?): observe PSF calibrator HIP 16339
Assuming elevation limit = +15 deg, move to Beta Pic at 20:30 local time.

Observation scheduled for the first half of the Jan 16 - Jan 17 night.
Beta Pic RA = 5h 47mn, DEC = -51 deg
Transit at 22:36 local time
Max elevation ~19.5 deg
Reaches 15 deg elevation 1h56mn before and after transit (local time: 20:40 and 00:32).

PSF calibrator is HIP16339, at RA = 3h 30mn and DEC = -47 deg 22'
PSF calibrator transits 2h17mn before target

Overview

All observations using 128x128 subarray, 30ms exposures (set to avoid saturation), 10 Hz cadence and 300ms higher SNR in PSF halo.
ADI mode using 589nm BS for AO
3 filters will be used:
  • 1537 nm, Hcont filter (peak flux in 30ms should be at 10000 to 15000 based on best frames acquired in the last run)
    • Unsaturated: 30ms, each cube is 500 images = 50s
    • Saturated: 300ms, each cube is 120 images = 50s
  • 1644 nm, FeII filter (peak flux in 30ms should be at 10000 to 15000)
    • Unsaturated: 30ms
    • Saturated: 300ms
  • 2269 nm, Kcont filter (peak flux in 30ms should be at 8000 to 10000)
    • Unsaturated: 30ms
    • Saturated: 300ms
No dithers, source placed near center of 128x128 pixels window (see figure below). Source will slowly move due to differential refraction between WFS visible light and imaging near-IR beam.
Example PSF obtained on Beta Pic in Hcont filter with 128x128 frame size and 30ms exposure
Peak value is ~1000, but if SR is good, it should be > 10000 (maybe 15000 ?).
The green circle shows the ideal position of the PSF center during the observation.

Observing sequence

If possible, acquire darks during the day before observation starts. Darks should be acquired in the same mode as observations: 128x128, 30ms and 300ms exposure. The darks will be used to measure readout noise for each pixel (last observations showed that the readout noise changes from pixel to pixel, and accurately measure dark level for 30ms exposure (even if it is low, dark level measurement is important for the "dark speckle" technique, to clearly identify what is the value of absolute dark).
Sky flats at beginning of night, when sky still bright
Telescope will be pointed to Beta Pic whenever possible, and reference PSF and sky will only be observed when Beta Pic is below elevation limit of the telescope.
16 mn sequence per filter, rotating between the 3 filters. Each sequence consists of 4 sets of alternating:
  • 2 mn of unsaturated exposures (2 short exposure cubes)
  • 2 mn of saturated exposures (2 long exposure cubes)
Page content last updated: 27/06/2023 06:35:52 HST
html file generated 27/06/2023 06:34:36 HST