Apr 08, 2026 UT: First test of Star Analyser, transits of Wasp-43 and Wasp-104, photometry of NN Boo

Michael Richmond
Apr 08, 2026

On the night of Apr 07/08, 2026, under excellent (but cold) conditions, PHYS 373 students, Anika Kumar, Dr. Melso, and I collected a large set of data on several objects:

• tests of the Star Analyser 100 on Jupiter, Capella, and the Eskimo Nebula
• exoplanet transits of
  • WASP-43b
  • WASP-104b
• photometry in B,V of the RR Lyrae star NN Boo (but only for a third of the period)

Tonight was clear and dark: very good conditions. There were no major instrument problems, although the finder's video camera slipped out of its drawtube and fell toward the floor. The BNC and power cables stopped it before it struck the concrete, but this is the second time that it has slipped out in the past few weeks. I'll have to examine the nosepiece and setscrew.

Star Analyser tests

Dr. Melso acquired a Star Analyser 100 and is working with one group of students in PHYS 373 to test it on our telescope. One of the images they acquired last night shows that we can achieve a rough focus and detect both the zeroth-order image and the first-order spectra of targets: this picture of the Eskimo Nebula (NGC 2392) shows the features clearly.

(North is up, East to left, field of view about 15 arcmin on a side)

Figuring out how to optimize data collection, and extract spectral information, will be an on-going project for this group.

WASP 43

WASP-43 has a transiting exoplanet, and was our first "regular" target for the evening.

These observations involved:

• Meade 12-inch telescope
• no focal reducer, so working at f/10
• ASI 6200MM CMOS camera
• clear filter, 60 sec exptime
• images binned 4x4
• no guiding
• focus position on 12-inch:
  • clear = 0.388 yields FWHM 3.5-4.0 pixels at T 17/-9

Notes from the night:

• sky was clear for the entire run
• no Moon until around 3 AM, when it was low in SE, behind trees
• camera at T = -15 C
• temperatures were very cold: T = 30/-1 at sunset, dropping to 23/-5 at 10:44 PM and 16/-9 at 4:49 AM
• quite a few students from PHYS 373, "Observational Astronomy," came to gather data for their projects

The picture below shows an image of the field of WASP-43 from the DSS2 red plates. The field of view is about 20 arcminutes wide.

WASP 104

WASP-104b has a transiting exoplanet. One group of our PHYS 373 class is hoping to measure the properties of the planet, using photometry of one full transit.

The chart below shows a region about 22 arcminutes on a side, centered on WASP-104.

NN Boo

NN Boo is a pulsing RR Lyrae star with a relatively short period of about 8.5 hours. If we can measure its average magnitude over the course of a cycle, we should be able to estimate its distance via the inverse-square law. How well will that estimate agree with the distance determined via parallax by Gaia?

The chart below shows a region about 22 arcminutes on a side, centered on NN Boo.

During this evening, I was able to acquire a series of images in B-band and V-band, using 60-second exposures in each. Over the course of about 3 hours, we collected 69 images through each filter, covering phases approx 0.60 to 0.93. That leaves a bit more than half the cycle to acquire on some subsequent evening.