My Variables Stars

As a follow up to the post on starting out observing variable stars I thought I’d talk about my journey.

I started variable star observing about four years ago with the naked eye and the 10-Star tutorial. I soon moved on to binocular variables, to which I’ve added a smattering of telescopic Mira variables now.

As you can see below, fuelled with enthusiasm soon clocked up 200, receiving a certificate from the AAVSO for my first 100, which was unexpected. Then the observation rate started to drop for various reasons including the appalling weather, British summer time (these two are often linked), and the pursuit of other astronomical interests. It stalled drastically after the first 600.

120 day binned cumulative variable star observations
My variable star observation count up to 19 January 2017.

Well at the end of 2016, I decided it was time to pick up the slack and at least push through the 1000 observations barrier, which I did on 5 October 2016. At the time I generated the chart for this post I was handful short of the 1100 observation mark, but another clear night has put me well over the top.

Choosing my variable stars

I’ve got a telescopic aperture limit of 6 inches and a relatively light polluted site so those exciting, but faint, cataclysmic variables are off the menu for me. Eclipsing binaries are fine, but the most valuable observations of these are CCD photometric these days: visual observers need not apply. Most of my efforts are aimed at Long Period Variables (LPVs) with a few other types thrown in for variety, and delta Cephei for nostalgia.

I choose variables to suit the magnitude range of my equipment and by constellation. The latter allows me to concentrate my effort in a smaller area of the sky: it’s an efficiency thing. I also have favourite constellations: it’s a personal thing, and possibly pragmatic too 😉

My back garden has a terrible horizon for an amateur astronomer. Houses block most of the lower 30 degrees of the sky to the south and east, there’s heavy light pollution to the west now from an industrial estate, but I’ve a much better northern horizon.

For that reason I tend to favour circumpolar constellations that are accessible all year round, providing an unbroken record of observations. I’m concentrating on Cassiopeia, Cepheus, Draco, Ursa Minor and Ursa Major.

There are currently 49 variable stars on my observing list of which I have to admit only 30 get regular attention at the moment, and all of those are in the constellations mentioned above.

Making observations

I use a combination of instruments depending on the brightness of the star and the sky conditions.

I can monitor variables with magnitude brighter than 5 with my naked eye (as long as I’ve got my glasses on!). A pair of 2.1x binoculars extends this to 7, but from around there down to magnitude 9 can be handled by a 10×50 binocular on a good night, and 15×70 binoculars for the fainter end on a night of poor transparency.

These can be pushed to magnitude 10, but around that I fall back on my first telescope: a Skywatcher 130P (130mm F5) newtonian. With the right eyepieces it provides good 1 and 2 degree field of view, which is plenty of room for the variable and comparison stars near the centre.

My final limit is about magnitude 12–13 depending mostly on altitude and transparency.

A good example is the recent CTA 102 quasar which reached around magnitude 11.5 and should have been possible. But by the time I had a clear sky – bad weather – CTA 102 was low in the western sky glow and had faded to magnitude 12.7. With the Moon right on its doorstep it proved just too faint for any of my telescopes. I suspected as much, but its not every day you get the chance to see something eight billion light years away with your own eyes, so I had to have a go! I found the field stars, but no quasar. I could have filed a “fainter than” observation, but it didn’t seem worth it when I was limited to 11.4.

I try to observe these rare opportunities – the Nova V339 Delphini and SN2014J in M82 spring to mind – as they’re not often within my range of magnitudes or a part of the sky I can see.

Making regular observations of selected stars really has its benefits though, quite apart from the fun of following their progress. Practice makes perfect and with the comparison stars fresh in my mind I can manage one observation every three minutes, which is quick by my meagre standards, and maintain this rate for a couple of hours.

I just noticed on the AAVSO website that I might get another award for the first 1000 observations. I also noticed that the next milestone is 5000!

Starting to Observe Variable Stars

If you’ve read the “about me” page you’ll know that I’m a fan of variable stars. Most of my astronomy colleagues think it’s a bit weird, but I love to test the ability of my eyes to judge brightness and follow the changes in the 30 stars on my regular programme. I now use my naked eye, binoculars and a telescope to observe variables, but I didn’t start that way… Continue reading “Starting to Observe Variable Stars”

The Veil Nebula in a small scope

I’ve become a little obsessed with observing this particular supernova remnant. I think it’s because it can show lots of nebulous goodness under less than perfect skies and with less aperture than some: it’s a realistic target.

That said, it’s not straightforward with a light polluted sky, but mid-summer is the best time to try with Cygnus right overhead, and that’s what I do every year.

I’ll admit to being a little late with this post, but I hope you’ll bear with me since this tale was certainly an observing highlight of 2016. Just imagine that it’s August and time to start my annual Veil Nebula hunt… Continue reading “The Veil Nebula in a small scope”

Observing in 2016

I guess it’s obvious that I wasn’t blogging much in 2016, but I have been writing for my local astronomy society newsletter which has obviously drained my creative well… that’s my excuse anyway.

I have be observing and probably more intensively than ever. Having posted a real article I thought I’d do a round up of my rough and ready observing statistics for 2016.

If you haven’t seen 2015’s and feel you need some context then “Observing Patterns” is the place to go.

How did 2016 stack up?

I keep a diary in which I note the weather conditions at night, whether I got out there, and if not what stopped me. Summarised here is the number of observable nights – remember my loose definition – and the number I actually observed.

My observing record for 2016

Not unlike the one from 2015. I averaged about 7 observing sessions per month last year too, and took advantage of 78% of opportunities presented.

The stand out month has to be June with one single session.

In my defence, the month of June isn’t ever dark here in the UK and the weather last year was miserable. As you can see there were only 5 nights available and they weren’t very good. In fact June 2016 was by far the worst astronomy month I’ve experience to date, so I at least have decided to cut me some slack 😉

So how was the Solar?

I think this chart tells the story very nicely.

My Solar observing record for 2016

I did a lot more Solar work in 2016 than in the previous year: 2016 had 67 sessions, whilst 2015 saw only 28. I also stretched the solar season a little too.

These are both white light, which increased, and hydrogen alpha observing sessions. I’m pretty happy with my solar progress last year and hope for more of the same. It’s been great fun.

Was 2016 what I expected?

For once I think things turned out much as I’d hoped… which can’t be said for many other aspects of 2016.

I’ve completed some solar sketching of both white light and hydrogen alpha features. I plan to carry on in much the same vein this year.

I concentrated on learning my lunar geography and geology over the last year, the result of which is that I’ve spotted some regions of particular interest for close study this year.

I revitalised my variable star observing towards the end of last year as I targeted 1000 submitted observations. I’m becoming even more stellar obsessed, so much more variable and double star action to come in 2017.

I’ve advanced my deep-sky observing skills whilst furthering my binocular census of the Messier objects, starting the Herschel 400 with small scopes and getting better observations of the Veil nebula using an even smaller scope (another story).

On a sad note, I soaked up the last of the planetary goodness for a while, observing Jupiter whenever it was visible. The gas giants are sinking way too low for me for the next few years. So despite recently observing the last of the major planets to escape me – Neptune – and last year spotting Titan in the C90, planetary observing isn’t likely to feature in 2017.

And of course, I expect to remain aperture challenged 😉

An Unexpected Moon

It was the 8th January 2017. The morning had been lovely with sunshine in place of the predicted fog! It didn’t last. As the afternoon wore on the clouds gathered and by nightfall not only covered the sky but had delivered a persistent drizzle.

So I didn’t expect much when I stuck my head out of the back door at around 22:20 UT. The first thing that struck me was how warm (6°C) it felt despite being dressed in a T-shirt and lightweight fleece pullover. Then I noticed how damp it felt: our local humidity was nearing 100% it seems.

Not expecting much I looked up to the south west and I noticed something bright. The Moon was punching through the rapidly moving clouds well enough to be quite observable!

The Moon at 10.7 days into its lunation
The Moon at 10.7 days into its lunation in Virtual Moon Atlas
Continue reading “An Unexpected Moon”

Observing Patterns

I’m alive, well and still observing… I’m just not writing about it much.

We’re halfway through the observing season and the weather in the UK hasn’t been helpful. I’ve still managed to clock some hours under the night sky, and I’m finding it useful to keep a record.

Keeping track of observing data.

In February last year I decided to start keeping track of my observing activities and the weather that sometimes kept me from doing so. At the end of the year I added up the totals and here they are.

Chart of my astronomical observing record for 2015

I should mention that my definition of clear is pretty generous. If there’s a half hour spell between the clouds, that’s a clear night; if it’s cloudy enough to make the constellations hard to see, but the Moon is about, it’s clear.

On the other hand, there will be times when it’s been clear but I haven’t noticed it. I have to admit that I don’t constantly watch the weather outside for a chance, and I do sleep too.

So caveat aside, what does this tell me?

Firstly it tells me that I took 77% of the opportunities to observe that the weather chose to present me.

It was a good start to the year, in fact so good that it enabled me to work out that other activities enforce a practical observing limit somewhere in the mid-teens. I’ve not been too far from that at times, which I’m satisfied with, and considering my other obligations and a couple of prolonged bouts of illness it’s been a good year overall.

Summertime blues

Unfortunately, the observing cliff in the middle of the year was partially due to the aforementioned illnesses, but more particularly two issues of orbital mechanics.

The first is that it doesn’t get properly dark until nearly midnight around the summer solstice, and only stays that way for a couple of hours. It never reaches astronomical darkness at that time of year, so some objects are very tricky for the analogue observer without GoTo as signposts can be few and far between. There are many of my deep-sky friends that completely close down for the summer: kind of inverse hibernation.

That said the skies weren’t bad. I experienced some lovely transparency and managed to find the Veil and North American Nebulae for the first time with a little help from my new Astronomik UHC filter. Little did I know that I’d come to miss those skies.

And then the solar system picks on me in particular because I do almost all of my observing from home, I don’t own a car, and I don’t like driving much anyway.

Having found joy in lunar observing early last year I discovered that the Moon never strays high enough in the summer to be visible over the top of the houses from my garden. The planets are rather low in the ecliptic at the moment too, and intend to stay that way for a few years! I couldn’t see Saturn from my garden at all… which was upsetting. I wasn’t pleased, but the Universe didn’t seem to care about that much, so I’ve had to make different plans. It did reduce the options to fill observing time in those bright summer evenings though.

My ST-80 on a photo-tripod provides a grab-and-go facility, but it’s not ideal for either planetary nor lunar observing. In an attempt to remedy this problem I’ve resorted to retail therapy and bought a Celestron C90 in the hope that greater mobility will help in 2016. I like this scope already: it’s compact and as easy to mount as the ST-80.

So what did I do instead? I found that the Sun puts in more of an appearance as the Moon plays hard to get, which is shown in by the number of solar sessions below.

Chart of my solar observing sessions in 2015

These seasons pick up the slack nicely and mean I don’t have to wait for it to get dark. I intend to do more white light and hydrogen alpha observing, and sketching, in 2016. Oh, and more nebulae too. They’re addictive.

Autumn!

Don’t worry, the dark nights are on their way I thought. Frankly what constituted a clear night in autumn (fall) 2015 had to be very broadminded.

We’ve had unusually warm and wet weather from the south-west which has produced the night time temperatures of summer, which never seem to happen in summer! It’s also brought lots of cloud.

What’s worse is that the moisture in the air has made even cloudless nights appear milky: washing out most deep-sky objects and many constellations. I was pleased to see the return of the Moon this winter, since the poor transparency has frequency made it the only game in town.

On occasion the Seeing has been a compensation: there have been really good spells. This has been perfect for observing lunar and double stars with a small refractor, which I do as much as possible.

Observing in 2016

Winter has yet to arrive at the time of writing, but the next few weeks look hopeful: forecast is for it to get cold and clear. I hope they’re right.

Tracking my observing through the last year’s varying conditions has caused me to consider my choice of equipment more carefully, and perhaps more importantly, diversify my observing goals. I’ve been asking myself, what gets me out there?

It’s one of those times that I’m glad I don’t own a big scope. My small scopes, with their rapid cooling time, can be in action in a few minutes without the need for an observatory. Perfect for the conditions I’ve been experiencing. I’ve decided to stick with them, so the 10–14 inch dobsonian mounted scope is shelved for the moment, since many of my autumn sessions have been a sequence of half hours between rain showers. It’s an interesting challenge to see what you can do with limited aperture.

I expect 2016 to contain much more lunar and solar sketching, the former for the winter and the latter in the summer. Double and variable star observing remains unchanged because I love it. The biggest change is that in addition to open clusters I’ve become obsessed with planetary nebulae. They’re an interesting test of your observing skills and many are accessible to small scopes from light polluted locations.

Partial Eclipse

The morning of the solar eclipse and looking to the East it’s not a pretty picture. I can see the location of the Sun, which is a major advance on yesterday, but it’s not even bright enough to show up through the solar filter… not good.

Optimism wins out, and I decide to set up the solar telescopes – white light and hydrogen alpha (Hα) – before having breakfast in the hope that luck will be with me today. It owes me a break since the night time trend is for me to get cloud when others get pristine skies.

Breakfast out of the way I’m asking myself whether it’s clearing. It looks like it is, but which way are the clouds going? I’ll take a look with the Herschel wedge on my ST-80. I can see the whole solar disk and think that the remaining light clouds lend an atmospheric touch as the sunlight bounces off them. But wait, is that a notch appearing in the circular face of the Sun? Yes! The game is on.

I watched the Moon slip across the face of the Sun, pausing to make notes and quick sketches of what I could see. The Sun is very active in Hα and some of the prominences became divorced from the Sun – detached isn’t the word, these were in limbo, now above the Lunar limb! I noted the time of first and fourth contact, and when a lonely sunspot group was occulted and later reappeared.

At maximum the temperature dropped, the sky took on a twilight feel, but the colour was different. Imagine a blue sky that’s fallen in luminance, a bit like that, purple for me and my dodgy colour vision. The birds actually clammed up, they’d been active until that point.

I noticed the temperature drop caught out the relative humidity. It had been dropping too as the morning progressed, but water was suddenly unhappy being vapour and my breath sent plumes across the garden. Weird would be a good word for it.

I could have imagined it, but it looked like there was some spillover of light onto the northeastern limb of the occulting Moon. In Hα I thought I could see some detail there. Very faint if it was real at all and not a product of the optics.

The house started to get in the way, so I had to be creative with the repositioning of my equipment around the garden to watch the next phase of the drama. But it was all there – much to my surprise – from beginning to end, first contact to the last.

An evening with the Pleiades

For those nights when you don’t want to spend an eternity tracking your target down it’s nice to have a plan that involves one of the brightest objects in the night sky. The Pleiades (M45) is handy for just this reason, and armed with a map and some doubles from the Washington Double Star catalogue (WDS) that’s what I decided to do on the night of the 6th January 2015.

A reversed image of the Pleiades from the Digital Sky Survey

Continue reading “An evening with the Pleiades”

M103 in Cassiopeia

It’s time for another open cluster, and in truth I’ve built myself a bit of a backlog. The issue is that I’m too lazy to scan my drawings in a timely fashion. That’s my excuse and I’m sticking to it.

This time I’ve chosen to turn my telescope, with pencil in hand, on M103 (one of Charles Messier’s objects) in the constellation of Cassiopeia for the second time this season. The first was with my ST-80, but I felt that 44x magnification didn’t to it justice. So on the night of 4/5 October I returned with the Vixen A80MF and 7mm Nirvana eye piece for a higher powered attempt (130x).

If you know what you’re looking for M103 isn’t hard to find being about 1 degree from the 2.5 magnitude star, delta Cassiopeiae. It’s not one of the “obvious” clusters, in fact I’m not sure why Messier found this one and not the nearby NGC 663, perhaps it looks more “cometary”.

My Observation

So once again, here’s a scan from my logbook. I’ve tidied up the notes on the computer, but the sketch has just had the contrast increased as the scanner leaves it a bit faint. My field of view is about 38 arcminutes with this telescope and eye piece combination.

Sketch of M103 in Cassiopeia

You’ll get to see the scan with handmade notes if you click on the sketch. And this is what the Deep-Sky Survey makes of M103.

DSS view of M103 in Cassiopeia

I don’t think I’ve done too badly.

Classification

To my eye, and telescope, M103 isn’t rich with stars. I’ve drawn pretty much all I could see, and some of those weren’t constantly visible. Yet there weren’t many more than a dozen stars in the cluster. So I classed this cluster as p (poor) using the Trumpler system.

There aren’t any really bright stars in M103, but there are obviously very faint ones (I estimate that I could see down to about 11.3 magnitude). This led me to settle on a brightness range of 2.

This cluster is clearly detached from the Milky Way background – quite a feat that was contested for some time after it’s discovery – and there’s concentration of the brightest stars, but its not highly condensed to my inexperienced eye.

So to reach my final Trumpler classification for M103 I threaded these components together estimating M103 to be a II2p open cluster of about 10 arcminutes angular diameter.

How does this compare with the official data? My estimate of the angular diameter is a little above the 6 arcminutes in the literature which also thinks that M103 is a bit richer giving it a rating of m rather than p.

I can live with that comparing my sketch with the DSS image.