On the night of Jul 22/23, 2023, under good conditions, I acquired images of
All data was taken with the 12-inch telescope and ASI camera. The results were mixed:
I pointed the telescope at a bright star and measured the focus in all filters. The results were
approximate
filter focus pos offset from R
--------------------------------------------
B 0.353 +0.020
V 0.335 0.000
R 0.331 0.000
I 0.309 -0.020
clear 0.329 0.000
---------------------------------------------
With the usual indoor flatfield setup -- shining an incandescent lamp across the dome onto a white posterboard -- the following exposure times yield reasonable levels in the ASI camera, binned 4x4.
filter exptime counts
---------------------------------------------------------------------
B 20 9,000 (takes too long as is)
V 8 19,000
R 6 18,500
I 8 20,000
clear 2 19,500
---------------------------------------------------------------------
I used the Orion StarShoot Autoguider Pro mounted in the off-axis port of the ASI camera, as shown in the picture below.
In order to focus stars on the guider's sensor, I slid the guide camera into the off-axis housing until the word "Orion" (just above the words "StarShoot(TM)") is roughly cut in half by the edge of the housing; see closeup below.
After clamping the guide camera in this position, I then twisted the housing's fine focus mechanism until stars were focused as sharply as possible; the vernier scale read "4" when in focus.
I wanted to calibrate the guider in MaximDL, and then use it during science exposures, but ran into problems. MaximDL could control the guide camera, so I could acquire images of stars; and it could compute the locations of stars in those images. But when MaximDL tried to send corrections to the Meade LX200 motors, there was no response.
I tried using the MaximDL "Move" button in the Guide window to move the telescope manually, but there was no apparent motion by the telescope in response to any choice of direction or requested slew size.
I tried using PHD2 to send small motions to the telescope motors, but it couldn't connect to the mount. Neither could ASCOM diagnostic programs.
I tried downloading and installing some drivers for the telescope
but it didn't help: programs claimed that they couldn't communicate with the mount, or simply didn't cause any motion when I pressed buttons to slew the telescope. Argh. Is it possible that some cables are bad?
It's been a while since I measured the color terms of the camera, so I figured I ought to give it a try. Using this page as a source of fields, I chose PG1633+099 and PG2213-006; the former was a bit past the meridian, and the latter a bit before the meridian during my observations between midnight and 2 AM.
In each field, I took a series of images -- 5 each with 20-second exposures -- through filters B, V, R, I. After analyzing the images several days later, it turns out that the measurements are _way_ too noisy to determine color terms properly. Look at the scatter from the mean as a function of magnitude:
I need to acquire a new and deeper dataset on these fields. Perhaps this would do the trick:
This is one of the stars that a capstone student may study over the next year in a project involving parallax. Ross 248 is a relatively faint red star surrounded by many other stars of similar brightness, so it's a good candidate for high-precision parallax measurements.
These observations involved:
Notes from the night:
The object is (currently) near position
RA = 23:41:55.27 Dec = +44:10:06.38 (J2000)
A chart of the field is shown below. The size of the chart is about 41 x 27 arcminutes. The noisy area at right (West) is the shadow of the guider's pickoff mirror.
I've marked the location of several comparison stars.
star UCAC4 B V r ------------------------------------------------------------------------- A UCAC4 671-120730 12.617 10.689 B UCAC4 671-120688 C UCAC4 671-120749 10.987 10.663 P kappa And 4.06 4.14 --------------------------------------------------------------------------
I took a photo of the finder TV's screen when pointing to Ross 248; this could be a useful reference for the future:
In order to get the best results for Ross 248, it is necessary to use only a subset of the stars in the camera's full field of view. For this evening's data, I chose the "intermediate" subset, and restricted matches to those stars within about 11 arcminutes of the target.
Here are the positions I've measured so far. The most recent measurements are at bottom right.
Like Ross 248, GX And is a nearby (binary) star which will be the target of a parallax project in the coming year. One of the two components is bright -- about mag V = 8 -- so one must use short exposures to prevent it from saturating the detector. That may mean that this system isn't as easy to measure as Ross 248 or some others.
On this night, for GX And,
The object is currently close to this position:
RA = 00:18:28.4 Dec = +44:01:31 (J2000)
but it does have a very high proper motion.
A chart of the field is shown below. The size of the chart is about 41 x 27 arcminutes. The noisy area at right (West) is the shadow of the guider's pickoff mirror.
The two components of the GX And binary sit inside the box. I've marked the location of several comparison stars as well.
star UCAC4 B V r ----------------------------------------------------------- A 671-001473 9.939 9.790 B 670-001639 9.413 8.472 C 671-001509 12.712 11.421 11.001 -----------------------------------------------------------
I took a photo of the finder TV's screen when pointing to GX And; this could be a useful reference for the future:
Using the same techniques as described for earlier nights, I matched detected stellar positions to the Gaia DR2 catalog, using all the stars in the "intermed" reference set.
The target is moving to the upper-right with time, and clearly shows the back-and-forth motion due to parallax.
V347 Aur is a young stellar object (YSO) which undergoes semi-periodic outbursts. I'm part of a team of astronomers who have applied for (and received) time on the XMM-Newton X-ray telescope to study this object in the fall of 2023. We have organized an observing campaign with the AAVSO to monitor the object in the optical in order to determine when the outburst begins -- if it begins! Our prediction is some time in mid-August, 2023.
The position of the variable star is
RA = 04:56:57.02 Dec = +51:30:50.9
At quiesence, it has magnitude V = 16-ish, but can rise to V = 12 in an outburst.
The object is just coming up before sunrise, so it was still very low in the sky when I acquired some V-band images this morning; the Sun was only 9-13 degrees below the horizon as well, so the image quality is pretty poor. Nonetheless, a stack of fifty 30-second images shows the variable clearly.
I've marked the location of several comparison stars.
star AAVSO ID B V ------------------------------------------------------ B 140 15.134 14.001 C 127 13.617 12.660 D 154 17.491 15.361 --------------------------------------------------------------------------
I measured a value of V = 15.84 and submitted it to the AAVSO.