The Variable Star Section report for 2017 has now been published.
It can be viewed via this link
It includes light curves for the stars on the section’s programme, based on observations submitted by section members.
Here, as an example, is the 4-year light curve for RW Bootis
Omicron Ceti (Mira) has brightened rapidly in recent weeks, with mid December observations placing it around magnitude 5.1 and early January seeing it around magnitude 3.7.
Mira has an average brightness range of around six magnitudes. The average peak brightness over the years has been magnitude 3.6, but the brightest maxima can surpass this by nearly two magnitudes. The average interval between maxima is approx 332 days – about 11 months.
The most recent maximum occurred in February 2017. Mira then started to fade but was lost soon after in the evening twilight. By the time that it emerged from the morning twilight in late July it was closing in on minimum brightness. Minimum, at around magnitude 10.0, occurred in early October. Mira then started to brighten. At first, the brightening was slow, but the rate of brightening picked up during November. With the next maximum predicted to occur in mid to late January, we can expect the rate of brightening to slow somewhat as maximum approaches. Given, however, that Mira was already this bright while still a few weeks of its predicted maximum date, it could be the case that Mira is heading for an early maximum or for a brighter than average maximum.
You can locate Mira using the accompanying finder chart.
Mira is located near to the head of Cetus (stars C, E, K and L). It is in a relatively bland area of sky, but the “V” of the Hyades helpfully points towards it.
You can follow the brightness changes of Mira by comparing its brightness with that of the stars labelled with letters.
In early January, for example, Mira was slightly fainter than comparison star E (mag 3.56), but was much brighter than comparison star G (mag 4.13).
You can read more about Mira via this guide
Here are predictions for eclipses that are reasonably favourable from the UK during November and December: Read more
The Mira type variable chi Cygni is due at maximum at around the end of October, but how bright will it be at its peak? Read more
As reported in the news item of July 23rd, following its early 2017 pause, R CrB had been edging brighter during the late spring and early summer. Read more
Here are predictions for eclipses that are reasonably favourable from the UK during September and October:
Times are in UT (same as GMT, 1 hour behind BST – so, for example, 22.7h UT is 23.7h BST) Read more
The Mira type variable R Trianguli is approaching its 2017 maximum.
Maximum is predicted for early September although, as ever, the exact date is always uncertain in advance by a week or two. Read more
There was a time when observers would be encouraged to monitor R Coronae Borealis (R CrB) on a regular basis to check for any sudden fades. The “standard pattern” was that R CrB would spend most of its time near magnitude 6.0 but at times, unpredictable in advance, it would start to fade. Read more
The Mira type variable Chi Cygni isn’t due to reach its peak brightness until late October … but it is already visible in binoculars. Recent observations place it at around magnitude 8.6. Read more
Four of the Mira type variable stars on the section’s programme – T Cep, R Ser, R UMa and T UMa – are currently near maximum and readily visible in binoculars. Read more