2016 Mercury Transit Observation by XRT

2016/05/09 11:11(1st contact) ----- 18:43UT(4th cont.)

Past observations with XRT

2006/11/08, transit of Mercury:

2012/06/05, transit of Venus:

XRT observation in 2016

• Included in the timeline to be uploaded on 5/7 (Sat).
• Two conflicting requests.
  • point on Mercury ( HOP 303 [Pasachoff et al.], SOT[polarization] and EIS[scattering])
  • DC pointing, i.e., more full-Sun full-res images (EPO [Yaji], PSF [Reale]).
• XRT is in eclipse season (continuous observation unable).

Suggested observing plan:
"Alternative (Mercury & DC) pointing for the periods separated by s/c eclipse+SAA events."
(use ecl+SAA period for FOV re-pointing and telescope stabilizing)

• 10:09 --- 10:41 (ecl+SAA event before Mer. contact-I)
• Period 1 (10:41--11:54) : Limb pnt. [73min] (see the Mer. approaching to the Sun, Mer.cont-I at 11:11)
• 11:54 --- 12:19 (1st ecl+SAA after Mer.cont-I)
• period 2 (12:19 -- 13:32) : DC pnt. [73min] (full-Sun + readout on Mer.)
• 13:32 --- 13:58 (2nd ecl. after Mer.cont-I)
• period 3 (13:58 -- 15:11) : Mer. pnt. [73min] (for SOT and EIS observation, Mer. CM passage at ~15:00)
• 15:11 --- 15:55 (3rd ecl.+SAA)
• period 4 (15:55 -- 16:49) : DC pnt.[54min] (full-Sun + readout on Mer.)
• 16:49 --- 17:31 (4th ecl.+SAA)
• period 5 (17:31 -- 18:28) : Limb(Mer.) pnt. or DC? [57min]
• 18:28 --- 19:08 (5th ecl.+SAA, Mer.cont-IV at 18:43)
• period 6 (19:08 -- 20:06) : Limb pnt.[58min] (see off the Mercury away from the Sun)
• 20:06 --- 20:45 (6th ecl.+SAA)

• Filter [Al-mesh] disk corona brightest. [Al-poly] requested from PSF study.
• image resolution 1x1 (size of Mer. : ~12 pix diameter at full-res.).
• image size : 768x384.
• cadence : ~ 30 sec
• speed of Mer. = 1292.6"/26363sec = 0.049 ["/s].
  sqrt((673+524)^2+(369-287)^2)/(5*60*60)=0.0666 --- from pos@12:50 & 17:50
• image quality v.s. CCD protection.
• Mer. exposure : 11 sec & 4 sec(in case of saturation)
• full-sun composite exposures : 16 sec, 4 sec, 128 msec.
• DC pnt readout : possible focus degradation.
• MDP bottle neck (cadence slow down).
• flare detection ON/OFF.

• ran on 3-May-2016 10:39 - 11:10.
• observing sequence:
  • full-Sun 2048x2048 3(long-med-short) exposures, 15 min. cad.
  • readout full-res 768x384 region. 2(11s 4s)exposures, 30s cad.
• solar activity: low.
• cadence was kept through the test (MDP bottle neck not occurred).
• Mer. exposure : 11 sec & 4 sec --> 8 sec & 4 sec?

Full-Sun images (click image to enlarge):

Al-poly 1x1 0.128sec	Al-poly 1x1 8.1928sec	Al-poly 1x1 16.3853sec

Readout images (click image to enlarge):

Al-poly 1x1 4.0968 sec	Al-poly 1x1 8.1928 sec
Al-poly 1x1 11.5725 sec	Al-poly 1x1 16.3853 sec

Final plan:

• XOB#1B30 for Mercury pointing and limb pointing
  (readout poining center with 512x512, with full-sun every 25 min.)
• XOB#1B2E and 1B2F for disk-center pointing
  (readout East and West 768x384 fixed area, with full-sun every 15 min, dark & G-band every 60 min).

Observation:

[bonus] Images from Hinode/SOT.
< click to enlarge > 2016/05/09 between 14 and 15UT