Horsehead Nebula Revisited

I decided to have another got at processing my recent Horsehead Nebula shot with some help from Bob Stuart.  I think I prefer the last one.

Sunspot Activity in Solar Cycle 25

With the skies being cloudy at night for sometime now and, with the recent development of some decent solar activity, my thoughts turned to the sun this afternoon. I didn't give myself much time as it was rapidly going down behind the neighbouring houses, but I did manage to get a couple of shots of the current active region known as AR 2781. 

Sunspots are temporary solar phenomena which are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. They are darker than the surrounding areas and occur in a region called the photosphere. Whereas the photosphere has a temperature of 5,800 degrees Kelvin, sunspots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them and they usually appear in pairs of opposite magnetic polarity as well as moving across the sun's surface.

The designation AR stands for Active Region and the sunspots shown in these photos are part of the current Solar Cycle 25. NASA had this to say on their website:

Solar Cycle 25 has begun. 

The Solar Cycle 25 Prediction Panel, an international group of experts co-sponsored by NASA and NOAA, announced that solar minimum occurred in December 2019, marking the start of a new solar cycle. Because our Sun is so variable, it can take months after the fact to declare this event. Scientists use sunspots to track solar cycle progress; the dark blotches on the Sun are associated with solar activity, often as the origins for giant explosions – such as solar flares or coronal mass ejections – which can spew light, energy, and solar material into space.

Here's a cropped version of the above photo to show the sunspots in a little more detail:

To take these shots I had to dig out the solar filter I made for the Transit of Mercury back in November 2019 when I began to take my interest in astronomy a lot more seriously. 

It's really important to never look at the sun without proper protection - this doesn't mean just wearing sunglasses or even using a welding mask.  It's very dangerous to look directly at the sun through binoculars, telescopes and cameras and solar filters are made of a very complex layered material which offers great protection.  Even then, I only ever view the sun by looking at an image on the back of my camera, never through the eyepiece.

The Baader AstroSolar Safety Film I used to make the filter renders the image as more or less white, and indeed, this is the true colour of the light coming from the sun.  The orange hues we see by eye are mainly due to dust in the atmosphere, although some specialised filters do give the images a deeper orange colour.  Here's a simulation of that created by simply increasing my camera's white balance control.

A Rather Frustrating Night

Tonight was rather frustrating to say the least.  Buoyed up by taking the Rosette and Heart Nebulae a couple of nights ago, I decided to move my tripod mount to the other end of my garden in order to see some different targets than the ones I've been imaging recently - bad move!  

In my original position I'd got setting up down to just a few minutes as the tripod was level and it was already pointing at Polaris making polar alignment quick and easy each time.  Moving the tripod meant that I had to level and realign it and for some reason tonight it just didn't go smoothly.  I'm not even sure now if I was aligned on the Pole star!

That said, I did manage a half decent photo of NGC 281 - the PacMan Nebula in Cassiopeia.  It's not as good as either of my two previously nebulae shots as the stars are not completely round. But it was great to locate it and get something that resembled the target, despite the smoke from Bonfire Night part 2 and my neighbours' patio lights shining directly in my face.  I used the same exposure as last time, 7 minutes at ISO 800 with an l-eNhance narrowband filter on a crop sensor camera modded for infra-red light sensitivity.

After this I redid my polar alignment and things seemed to get worse!  Clouds were also starting to appear so I started rushing things and quickly went for B44, the famous Horsehead Nebula in Orion. I only had time to do one single shot and, whilst doing it, I managed to click the tripod resulting in the 'tadpoles' you can see in the image below.  In spite of all this, I was very pleased to see the horse's head pop out of the nebula as this was the first time I've ever seen it. This single record shot took quite a lot of processing to remove noise and make it acceptable for viewing. But don't worry, I'll be revisiting this one a few times this winter!

I finished the evening on a patch of cloud-free sky almost directly overhead and fortunately M45, the Pleiades in Taurus were showing quite well there.  I've never managed to bring out much of the nebulosity in this open star cluster, and the same was true of tonight. Another one to revisit methinks.

First Light with my Astro-modded Camera and Narrowband Filter

My recent acquisition for doing astrophotography is a Canon 800D DSLR camera body which I had modified for astro work. Now I am a Nikon user and it pained me to buy a Canon camera, particularly when I have two older Nikon bodies which could have been used.  However, three factors influenced my decision to buy a Canon body. Firstly, it is ridiculously expensive to have a Nikon camera modified for astrophotography in the UK and very few places do it. Secondly, neither of my old Nikons have a swivel screen and I have found having this on my D500 invaluable.  But I'm not going to have that body modded as it's my main birding camera. Thirdly, I know several people who use this model of camera to good effect and it's still a current model.

The modification involves removing the infra red (IR) filter (which is fitted to most new cameras) in order to make it more sensitive to the Hydrogen Alpha (Ha) wavelengths of light.  Many deep sky objects emit Ha light and normal DSLRs find it difficult to image these wavelengths.

In addition, I recently bought an Optolong L-eNhance narrowband filter to cut out unwanted light-pollution from houses, street lights and the moon as well as improving the contrast of Ha emission nebulae.  But when I took some initial shots with it on my unmodified Nikon camera, I realised it wasn't going to work well.  So I ended up buying a second hand camera body to have modified for increased sensitivity.

This session was my first attempt at using both the filter and modded camera together, and I have to say I am pretty pleased with the results.

My first target was NGC 2244, the Rosette Nebula in the constellation of Monocerous near to Orion. Although the initial image didn't look like this, I could definitely see the red Ha light faintly on the back of the camera and processing it in PhotoShop CC brought out these details.  It is a single shot of 7 minutes duration at ISO 800 on an HEQ5 Pro tracking mount. I didn't use guiding and so the stars are amazingly round for this duration of shot.

Later I took this shot of IC 1805, the Heart Nebula in the constellation of Cassiopeia and, although I should have used a focal reducer to get the whole image in the frame, I am pleased with my first attempt. The exposure was the same for the Rosette Nebula as described above.

With these two successful targets under my belt I am now keen to get guiding going and do some stacked sets of shots to hopefully bring out more fine detail and perhaps some more colours.  I'll also be using a focal reducer on both of them next time.

Another Labelled Moon Map

One of the things I really like doing is putting labels on my astro images, particularly the moon and constellations. This really helps me learn and remember these things and I fnd that many other people write positive comments about the labelling when I post in various Facebook groups.

So here's a labelled version of last night's waning gibbous moon: