June 9-12, 2011
The target is a new candidate qLMXB found in the J1655 field of the
ChaMPlane survey. It resembles the black-hole X-ray binary GRO J1655-40, with
a subgiant secondary and orbital period of 2.62 days
Object Type RA (J2000) Dec (J2000) nH/10^22 Dist Mv R log(F_X/F_R) log(L_X)
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New qLMXB G4-6IV 16:54:08.14 -39:56:36.1 0.4(1) 2.2kpc ~3.0 16.19(2) -2.7(5) 31.0(7)
J1655-40 F5IV 16:54:00.14 -39:50:44.9 0.6(1) 2.8kpc ~1.2 16.14(1) -2.9(4) 30.9(7)
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Teleascope Pointing 16:54:04.14 -39:53:40.6
The Y4KCam is a 4Kx4K CCD camera with 20'x20' field of view. The CCD
has excellent blue sensitivity, especially at U-band. The resolution
is 0.289"/pixel.
The New qLMXB candidate and J1655-40 are only 6' apart. Use the above
telescope pointing to cover both objects.
Here are the founding charts: New qLMXB. 2.5'x2.5' N-up. E-left.
New qLMXB and J1655-40. 9'x9' N-up. E-left.
Use
SDSS u,g,r,i,z to take light curves continuously. 3-5min exposures.
Take a few B, V, Rc, Ic images for reference. No need to take
photometric standard, as J1655-40 are well calibrated.
CTIO Yale 1-m Telescope Y4KCam Filter Transmissions
postscript
The
astronomical twilight on June 9-12, 2011 ends at 19:16 and begin at
6:10 local time. There are 10h56m from evening to morning twilight.
Try to start 10-15 min before and to end 10-15 after the astronomical
twilight zone to get a little more observing time.
Here is an observing elevation chart.
postscript
CTIO 2011 june Ephemeris
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- Biases and Domeflats: Take biases and domeflats in the afternoon before dinner.
- Skyflats: Take twilight skyflats starting shortly after sunset at around 6:00pm.
- Pointing and Focus: Do telescope pointing and focus after the skyflats at around 6:45pm.
Use command "zero" to take 15 biases, and use command "doobs" to
take 7 domeflats each (V R I & Ha) in sequence, in each afternoon
before observing. Dark is not necessary.
Take some skyflats in the
evening or morning twilight if possible. I filter skyflats are
probably the most needed in order to correct the fringes. Ideally,
dark skyflats made from object fields (or blank skys) are the best.
But there are too many stars in the Galactic plane which makes this
impossible (and we don't have time to spend on taking blank skys). So
we need to take some twilight skyflats. Timing is very crucial for
this. Here are some simple steps for doing evening twilight skyflats:
- Point the telescope to zenith at sunset at 6:00pm.
- Turn the tracking on during the skyflat exposures and turn the
tracking off during the readouts so there will be an offset between
exposures.
- Do the Ha filter skyflats first, then do the I filter skyflats.
- Start at about 6:10pm, take a 2 seconds Ha skyflats. Examine the
image and make the adjustment of the exposure time so the flat has
about 10000 counts.
- Take the first Ha skyflats with adjusted exposure time (remember to turn
the tracking on during exposure and off during readout).
- Take the second Ha skyflats with exposure time twice as long as the first
exposure (e.g.: first is 5sec, second one should be 10sec). The sky gets
darker during the 1.7 min readout. To double the exposure time is
just about to compensate the change in the sky.
- Take at least 3 Ha skyflats.
- If the exposure time is still under 30sec, continue to take the Ha
skyflats until the the exposure time is over 30sec.
- Take the first I filter skyflat with exposure time equal to 1/10 of the
last Ha skyflat exposure. Examine the image to make sure it gets about
10000 counts. Adjust exposure time if needed.
- Take the second I filter skyflat with exposure twice as long as
the first.
- Take at least 3 I skyflats.
- Stop the skyflats at around 6:45pm.
- Do the pointing and focus at around 6:45pm.
- Start to observe the first ChaMplane field at about 7:03pm.
The quiescent light curve and the evolutionary state of GRO J1655-40
The quiescence optical light curve of Nova Scorpii 1994 (=GRO J1655-40)
The black hole transient Nova Scorpii 1994 (=GRO J1655-40): orbital ephemeris and optical light curve
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Ping Zhao: zhao@cfa.harvard.edu
pogo3.cfa.harvard.edu