Comet C/2022 E3 (ZTF)

We have another brightish comet gracing our skies at the moment and this is C/2022 E3 (ZTF). The Comet is currently in the constellation of Bootes and heading north towards Draco (see the graphic by Pete Lawrence in this article by the Sky at Night magazine). It is currently about 6th magnitude and so it is approaching naked eye visibility.

On Sunday morning (the 15th January) I had woken up early and not been able to get back to sleep, so I went to see if I could find this comet. We had clear skies and it wasn't difficult to locate using 7x50 binoculars as it was roughly halfway between the stars Beta Boo and Eta Her. Not wanting to go outside and endure the sub-zero temperatures, I decided to try and make a drawing of what I could see but I had to lie on the floor to get a decent view. This is what I saw:-

The stars 2, 4 and Chi are part of Hercules and Nu 1, Nu 2 and Phi are part of Bootes. The comet is the smudge near the centre of the field. I started the observation at 4:34 UT and finished at 5:22 UT. There was a last quarter moon shining in the south and so the sky wasn't that dark. I compared the comet to M13 (a globular star cluster in Hercules) which is visual magnitude 5.8 and I thought it was fainter than this but perhaps twice the area. The comet was estimated to be magnitude 6.5 at the time.

All text and images © Duncan Hale-Sutton 2023

GO Pegasi 9th January 2023 - part 2

The other variable star that I had a look at a week ago was GO Pegasi. I haven't observed this star before and it is conveniently located roughly halfway between alpha and lambda Pegasi at the right-hand side of the square of Pegasus. The BAA chart 103.02 places GO near the star Flamsteed 51. According to the BAAVSS this is another semi-regular variable (SRb) with a main period of about 79 days and a range in luminosity of between 7.14 and 7.91 magnitudes (so not very large).

At 18:50 UT I saw that GO was fainter than star B (=7.0 mag.) on the chart and at 18:57 I estimated that it was marginally brighter than star E (=7.8). So my estimate was B(3)V(1)E which made it magnitude 7.6.

I think this is in pretty good agreement with observations from the BAAVSS and the AAVSO.

All text and images © Duncan Hale-Sutton 2023

RW Cephei 9th January 2023

On Monday, in the early evening, we had some clear dark skies before the moon came up and so I was able to make a couple of variable star observations. The moon was 3 days past full and wasn't due to rise until 18:32 UT. Twilight ended at 18:10.

I started off with another observation of RW Cephei. The constellation of Cepheus at this time is still relatively high in the sky. At 18:24 UT I noted that RW was fainter than star E (=7.3 mag.) on BAA chart 312.02 but not by much. At 18:27 I confirmed that RW was brighter than star H (=7.8 mag.) and so my estimate was it was 1 "point" from E and two "points from H (or E(1)V(2)H). This made it magnitude 7.5 to 1 d.p.

This means that, in my estimation, the star hasn't shifted in brightness since Christmas Eve 16 days ago. However, my estimate seems slightly at odds with what other members of the BAA are seeing.

The above light curve courtesy of the BAAVSS shows all the data between the 01/01/2022 and the 09/01/2023. The last data point to the extreme right is the observation I have made here. It seems my magnitude 7.5 values are probably 0.2 magnitudes from the mean and on the upper edge of the spread of values. I find it hard to understand how the estimates could be as faint as magnitude 7.9 as this would mean that it was fainter than star H which I am pretty sure it wasn't.

Here is the light curve for this star from the AAVSO:-

What is interesting here is that AAVSO shows a similar spread in values between about 7.4 and 8.0 magnitudes but curiously CCD measurements (shown in green squares) can't quite agree either even though these should be much more accurate than visual observations. Note that there is a marked increase in the number of observations around JD 2459929 (16 December 2022) as this was when an alert from the AAVSO went out asking for more data. Prior to this date one observer (VOL) had a nice sequence of DSLR observations (in green squares) with very little scatter. Here is his data shown on its own:-

This observer seems to be seeing what I see in that dimming of RW is flattening out and tending to magnitude 7.5 (however, there may be a 0.2 magnitude systematic difference between visual and DSLR observers).

All text and images © Duncan Hale-Sutton 2023 except those by the BAAVSS and AAVSO.

Mobile phone picture of the Moon

Later on Monday evening (the 2nd January) I thought I would have a go at photographing the moon using my mobile camera (a Samsung Galaxy A21s) and my Orion OMC-140 Maksutov-Cassegrain. I have heard that it is possible to get quite good pictures by holding the camera lens up to the eyepiece of a telescope and taking a picture 'afocally'. The difficulty in doing this by hand is getting the telescopes image of the moon lined up with the camera of the phone and then holding it steady enough so that a picture can be taken. However, after some experimentation I did get one shot that I thought was pretty good:-

Here I used a Celestron 25mm eyepiece and the camera settings were 1/50s at f/2, ISO40. This was how I saw the image in the eyepiece. I was using a star diagonal, so even though North is at the top East is to the right and West to the left (which is the opposite way to which we usually see the moon with the naked eye). I was really impressed with the results and may try and do more work with my phone camera, perhaps purchasing a holder that can attach to the eyepiece to keep everything steady. If you 'click' on the image you can get an enlarged view which will show more of the detail of the 'seas', mountain ranges and, of course, craters.

All text and images © Duncan Hale-Sutton 2023

A low apparition of Venus on the 2nd January 2023

On Monday this week we had some nice clear conditions in the late afternoon and so I thought I would go out and see if I could find Venus and Mercury. In fact, it would have been virtually impossible to see Mercury as it was lost in the glare of the setting sun. You can use the BAA computing section's applet to find the position of the planets (and other objects) at any time. I did find Venus and so I got this image at 16:39 UT:-

This was about 34 minutes after sunset and Venus was about 4.4 degrees above the horizon (at this time Mercury was just 2.2 degrees above that level). This is looking almost SW. At the present time Venus is emerging from conjunction with the sun and will reach its greatest elongation east on June 4th. Its apparent diameter is quite a small 10.4 arc seconds and the phase is about 96%.

All text and images © Duncan Hale-Sutton 2023

Geminid Meteor Shower 13th December 2022

Two weeks ago we had the Geminid meteor shower which peaked over the night of the 13th/14th December. The moon on this date was waning gibbous and about 3 days from last quarter. It rose about 20:44 UT and so would interfere with observations after this time. Nevertheless, this is now the best meteor shower of the year and so I decided to see if I could capture any events on my camera.

I am glad to say that I was quite successful in spite of the moon. In all I caught 6 meteors on camera in the period 22:00 UT (approximately) to 23:17 UT. I had a few problems to begin with and it took me a while to settle on a successful method. After 22:18 I had the correct date and time (UT to the nearest second) recorded in my camera (prior to this I still had the year as 2021! and the time was out by a few minutes). At 22:27 I settled on taking successive 15 second exposures at ISO1600. I was using a D90 camera with a 18-105mm lens set at 18mm. This gave me a field of view of about 66x46 degrees. I made a note of the frame numbers where I had seen a meteor which was in or near the part of the sky where the camera was pointing.

I noted that I had seen 10 meteors in all. Initially I was pointing the camera south and then later I pointed it east. The first meteor I detected was this one at 22:18 UT.

This was a 30s rather than a 15s exposure. If you click on the image you will see an enlarged version. The meteor crosses the boundary between Orion and Taurus near pi 1 Orionis. The Hyades, Mars and the Pleiades can be seen clearly above the short trail of the meteor.

The second meteor that was recorded was at 22:42.

This one is more difficult to see but it is found just above the cloud to the right of Orion. This meteor lies entirely in the constellation of Eridanus near 47 Eridani.

The third Geminid was the best of the night and recorded at 22:45 UT.

This was a bright meteor and as bright as Mars which was nearby and magnitude -1.8. It also had a similar yellowish orange colour. The trail starts in Taurus (passing 5 Tauri) and ends in Cetus crossing a little bit of Aries. A couple of things to note: 1) there is a bit of ghostly train left behind the trail where the meteor has passed and 2) the trail is wiggly in structure near the start. This latter point may have been caused by camera shake as the meteor appeared very shortly after I pressed the camera shutter. However, Mars is just as bright and there is no camera shake noticeable in its image.

The third meteor I detected was at 22:54 UT.

This was a noticeable meteor and can be seen just above the figure of Orion the hunter. The trail of this meteor starts in Orion but then crosses into part of Taurus (it ends between 131 and 133 Tauri).

The next meteor to be captured was at 23:08 UT. By this time I had moved the camera to look eastwards.

This one is very faint and difficult to see. The short trail appears in the constellation of Cepheus not far from the triangle of stars made by delta, epsilon and zeta.

The final capture was at 23:12 UT.

This meteor is in virtually the same part of the sky as the previous one but, perhaps, a bit brighter. It passes between 18 and 19 Cephei.

All text and images © Duncan Hale-Sutton 2022

RW Cephei 12th and 24th December 2022

I decided to have a go at observing a different variable star this month and that is RW Cephei. The star is located near the triangle of stars made by zeta, delta and epsilon Cephei (the "foot" at the base of the constellation's main rhombus of stars). RW is a red hypergiant whose apparent brightness ranges between 6.0 and 7.6 over a period of about 346 days. It is classified as a semi-regular SRd type. Earlier this month this star has become the focus of attention because it may be going through a period of exceptional dimming as did Betelgeuse in Orion in January 2020.

I had a look at this star on Monday the 12th December 2022 in the early evening. At this time the moon was 4 days past full and not due to rise until 19:32 UT. At 18:30 the sky was clear and dark and astronomical twilight had just ended.

At 18:32 UT RW was fainter than star E (=7.3 mag.) on chart 312.02. At 18:50 UT I thought it was marginally brighter than star H (=7.8 mag.) and my estimate was E(2)V(1)H or magnitude 7.6 (to 1 d.p.).

I had another go at this star a few days ago on Christmas Eve (24th December). Then it was just one day past new moon and again the sky was clear and dark but there may have been a slight mist.

At 18:45 UT RW was again fainter than star E (=7.3 mag.) but this time it was closer brightness to this star than star H (=7.8 mag.). My estimate at 18:55 UT was that it was E(1)V(2)H or magnitude 7.5. So not much different to 12 days ago.

I don't have much to compare my results to as there hasn't been any further data added to the BAA VSS database by other observers since the 10th December, though one BAA VSS member did say that he had measured it to be visual magnitude 7.7 on the 21st December (via baavss-alert).

All text and images © Duncan Hale-Sutton 2022