XRT Stray Light Study 5 & 6 -- Measurement and Correction.

(12 August, 2014 by Aki Takeda)

1. Purposes of the tests.

Purposes of the 5th test (performed in the 2014/07/29 timeline).

• collects light curves of the XRT eclipses.
• first attempt to obtain Med-Be and Med-Al stray-light images.

Purposes of the 6th test (performed in the 2014/07/31 timeline).

• collects more light curves of the XRT eclipses.
• second attempt to obtain Med-Be stray-light image (re-take).
• first attempt to obtain Thick-Al and Thick-Be stray-light images.

The tests were performed on:

• 29-July-2014, 17:53 -- 18:03UT (for Med-Be --- failure! wrong size).
• 30-July-2014, 18:30 -- 18:40UT (for Med-Al).
• 31-July-2014, 15:49 -- 16:00UT (for Med-Be --- success!).
• 31-July-2014, 17:27 -- 17:40UT (for Thick-Al).
• 1-August-2014, 16:26 -- 16:37UT (for Thick-Be).

Solar condition.

2. Test sequences.

Med-Al sequence (2014/07/30).

• 18:15:00 -- s/c pointing to disk center (0,0)
• 18:18:00 -- regular synoptic program.
• 18:30:00 -- test sequence started (until ~18:40).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
  • 1024x1024 pix, 2" resol., Full-Sun, Med-Al long/short exposures.
  • 256x256 pix, 2" resol., every 10 sec on AR12125, Ti-poly + G-band(VLS close).
  • 1024x1024 pix, 2" resol., every 60 sec, Full-Sun, Med-Al.
  • detailed parameters of the sequence (XOB#1A2B).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
• 18:33:00 ------ XRT entering twilight zone.
• 18:39:30 ------ XRT s/c night entry.
• 18:53:30 ------ XRT SAA entry.
• 18:53:30 ------ XRT s/c night exit.
• 19:00:30 ------ XRT exiting from twilight.

Med-Be sequence (2014/07/31).

• 15:45:00 -- s/c pointing to disk center (0,0) for SOT flat field cal.
• 15:49:30 -- test sequence started (until ~16:00).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
  • 1024x1024 pix, 2" resol., Full-Sun, Med-Be long/short exposures.
  • 256x256 pix, 2" resol., every 10 sec on AR12125, Ti-poly + G-band(VLS close).
  • 1024x1024 pix, 2" resol., every 60 sec, Full-Sun, Med-Be.
  • detailed parameters of the sequence (XOB#1A2E).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
• 15:52:30 ------ XRT entering twilight zone.
• 15:59:30 ------ XRT s/c night entry.
• 16:15:30 ------ XRT SAA entry.
• 16:15:30 ------ XRT s/c night exit.
• 16:20:00 ------ XRT exiting from twilight.

Thick-Al sequence (2014/07/31).

• 15:45:00 -- s/c pointing to disk center (0,0) for SOT flat field cal.
• 15:49:30 -- stray light measurements for the Med-Be filter performed.
• 17:18:00 -- regular synoptic program.
• 17:28:00 -- test sequence started (until ~18:00).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
  • 1024x1024 pix, 2" resol., Full-Sun, Thick-Al long/short exposures.
  • 256x256 pix, 2" resol., every 10 sec on AR12125, Ti-poly + G-band(VLS close).
  • 1024x1024 pix, 2" resol., every 60 sec, Full-Sun, Thick-Al.
  • detailed parameters of the sequence (XOB#1A2C).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
• 17:31:00 ------ XRT entering twilight zone.
• 17:38:30 ------ XRT s/c night entry.
• 17:51:00 ------ XRT s/c night exit.
• 17:52:30 ------ XRT SAA entry.
• 17:58:00 ------ XRT exiting from twilight.

Thick-Be sequence (2014/08/1).

• 16:15:00 -- s/c pointing to disk center (0,0)
• 16:18:00 -- regular synoptic program.
• 16:26:00 -- test sequence started (until ~18:40).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
  • 1024x1024 pix, 2" resol., Full-Sun, Thick-Be long/short exposures.
  • 256x256 pix, 2" resol., every 10 sec on AR12125, Ti-poly + G-band(VLS close).
  • 1024x1024 pix, 2" resol., every 60 sec, Full-Sun, Thick-Be.
  • detailed parameters of the sequence (XOB#1A2D).
  • -----------------------------------------------------------------------------------------------------------------------------------------------
• 16:29:00 ------ XRT entering twilight zone.
• 16:36:30 ------ XRT s/c night entry.
• 16:49:00 ------ XRT s/c night exit.
• 16:51:00 ------ XRT SAA entry.
• 16:56:00 ------ XRT exiting from twilight.

3. Results of the test observation.

3.1 Sunset light curves

at the time of Med-Al measurement.

at the time of Med-Be measurement.

at the time of Thick-Al measurement.

at the time of Thick-Be measurement.

close

3.2 Stray light images

• Med-Al (32 sec exposure)

Med-Al stray light images obtained (movie).

No significant stray light detected. Slight enhancement at the center of CCD (known as the smudge).

• Med-Be (23 sec exposure)

Med-Be stray light images obtained (movie).

No significant stray light detected. Slight enhancement at the center of CCD (known as the smudge).

• Thick-Al (64 sec exposure)

Thick-Al stray light images obtained (movie).

No significant stray light detected. Slight enhancement at the center of CCD (known as the smudge).

• Thick-Be (64 sec exposure)

Thick-Be stray light images obtained (movie).

No significant stray light detected. Slight enhancement at the center of CCD (known as the smudge).