V0446 Vul

The variability of this star was discovered by Lennart Dahlmark in a photographic patrol programme, using plates exposed from 1967 and onwards. It was announced in a publication in 2001.1 Two years later it got the official designation V446 Vul.

Dahlmark gave the type Lb, a slowly varying irregular variable. However, a handful of recent observations by me shows the variation to be rather fast:

Recent observations of V446 Vul

V0446 Vul is included in the ASAS survey, which also shows a rather quick semiregular variation on a timescale of about 100 days:

ASAS observations of V0446 Vul

I have used the Fourier period analysis tool (DC DFT) in Vstar to analyze the ASAS observations, and the result is 103 days.

V0446 Vul seems to be some kind of SR variable, rather than an Lb.

Update 26 August: now the VSX entry for V0446 Vul has been revised to show the new data.

  1. Dahlmark, Lennart. ”New Variable Stars Along the Northern Milky Way”. Information Bulletin on Variable Stars 5181 (2001). []
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C/2014 E2 (Jacques)

I observed C/2014 E2 (Jacques) with 15×70 binoculars tonight. Magnitude was estimated to be 7.0, using the Sidgwick method and an AAVSO sequence of comparison stars for the nearby V0465 Cas, coma diameter 6′. The observation has been reported to COBS.

The comet was very easy to spot and showed no tail. Observations with my 90 mm Maksutov Cassegrain at 50x and 187x showed no tail, and the comet appeared brighter and larger with the binoculars than with the telescope.

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BRT queue

Four days later, and still no images from BRT. No big deal, but the queue seems to be rather long.

Update 25 August: a week after registration, the first four images came through. Quite good tempo, I think.

Update nr 2 26 August: yet four more images came through the queue.

Update nr 3 28 August: two more images. Summing up, ten images came through during eleven days. If this is typical of the average throughput of the BRT system, 3 pounds per month seems like a very good price, compared to Sierra Stars and iTelescope.

Update nr 4 17 September: one month, 20 completed images. Cheaper and deeper than iTelescope.

Update nr 5 17 October: yet another month, in which 27 images were taken. The tempo is quite OK.

Update nr 6 17 November: 19 images this month. After three months, the average cost per image lies at 14 pence = 22 US cents = 1.6 SEK. For comparison, the minimum price over at Sierra Stars (30 seconds on the Rigel 37 cm Cassegrain) is 42 US cents, while a 30 second exposure on iTel 5 (25 cm Newton) is 58 cents (lower when there’s a moonlight reduction in price).

So, not surprisingly BRT turns out to be cheapest of the three compared systems. That doesn’t mean that I will leave Sierra Stars and iTel for BRT. The latter system is cheaper, but I have greater control over what images will be taken, and when, using Sierra Stars and BRT.

I have kind of taken to BRT, though. The images are great, even though there’s often some trailing but I can live with that for my photometry of variable stars, they reach deep. The user interface is quite good, just like Sierra Stars it is of the fire-and-forget variety, iTel takes a bit more handling to get going, what with booking the scope and everything. And the BRT tempo suits me; roughly 20 images a month leads to images showing up every once in a while, perfect for some photometry during lunch breaks.

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Bradford Robotic Telescope

I like the BRT, when there’s no trailing the images are deep and I can measure down to the 16th magnitude or so. The major drawback is, I would say, that the telescope is severely oversubscribed. I’ve been off BRT for quite some time, instead using iTelescopes 4 and 5, but now I’ve resubscribed. My old account was of a type that don’t exist anymore, and instead I opted for the 3 pounds per month type of account, which lets you have ten images in the queue.

Three pounds per month leads to a quite cheap price per image compared to iTelescope and SierraStars, provided those images gets taken. Wonder how long it takes before those ten images gets through …

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LD 323

LD 323 is one of the Lennart Dahlmark variables that so far has not made it into the GCVS namelists; and lacking an official name we will have to keep calling it LD 323 for some time. I have observed it on and off for about a year. There is also a series of observations by Steve Girard in late 2013.

The star varies quite regularly:

A year's observations of LD 323.

I have used VSTAR to analyse Girard’s and my observations. The Fourier transform method (DC DFT) in VSTAR gives a period of 88.9 days (using only the V data), which is for all practical purposes identical to the result, 88 days, that Sebastian Otero got in his analysis of NSVS data for this star.

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Nova Cygni 2014

Nova Cygni 2014 has been behaving in an interesting way; overlayed on the general rise to max and decrease after max, are variations with an amplitude big enough to be prominent in visual observations.

Observations of Nova Cyg 2014 from the AAVSO archive

I have observed the nova a number of times, using the 90 mm Maksutov-Cassegrain. It is easy to find, with star hopping-friendly asterisms nearby. It is the third nova I’ve observed recently, the other two being Nova Cep 2014 and Nova Del 2013, also known as V0339 Del.

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Guerilla astronomy

The weather forecast for the coming days shows some chances of partly clear skies at night, but the odds are not very good.

As usual.

My 20 cm Newton is kind of bulky, and not the type of instrument one quickly sets up to observe through gaps in the clouds (I don’t have it permanently mounted, have to carry it outside for observing). No, for nights such as tonight, I rather prefer my 15×70 binoculars and my 90mm Maksutov-Cassegrain, small instruments that are easily and quickly set up in my backyard.

90mm f/13.9 Maksutov with 8x50 finder. The telescope has a quite decent limiting magnitude of 12.4 with my 6.7 mm Explore Scientific eyepiece, even when observing from my urban location.

In a number of minutes, one is set up to observe. The pair of 15×70 binoculars is a fast instrument, and the 90mm Maksutov-Cassegrain reaches 12, even 12.4 on a good night (from my urban location). I use the same 8×50 finder with the Mak and with the 20 cm Newton, which speeds up starhopping. It is mounted on a Triton alt-az mount which is sufficiently stable, even at 185x.

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Lightcurve: T Cep

First in the series of posts on lightcurves is T Cep, which has become one of my favorite variables. It is circumpolar, which is always a nice thing – no season gaps in the light curve. Also, it clears the neighboring five storey house during winter and spring, which means that I can follow it all year around from my backyard, without moving about. 15×70 suffice most of the time, but I need a telescope to pick it up near minimum.

I’ve followed T Cep since late October 2011, through three maxima and two minima. The minima look more or less the same, while the maxima have quite different forms:

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I’ve been observing variables since late October 2011 (plus a stint as a variable observer as a student in the late 1980′s), so for some variables I have now collected so many observations that I can plot light curves spanning reasonably long periods of time. I thought I’d begin an irregular series of posts of such light curves here on the blog.

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Nova Delphini 2013

Koichi Itagaki has discovered a bright nova in Delphinus. After spectroscopic confirmation, it got the official designation Nova Delphini 2013.

At first, the sky over Lund was cloudy. I waited and waited, but at about 02 local time (00 UT) I gave up and went to bed. However, some 45 minutes or so later I awoke and decided to leave bed and was greeted with a clear sky!

The nova was easy to find and I estimated its brightness to be 6.0 at August 15, 00.50 UT using 6×30 and 15×70 binoculars. The sequence used was an AAVSO chart, with convenient comparison stars at 5.7 and 6.2.

After that, the nova appears to have brightened somewhat:

Looking forward to following this bright nova!

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