Both my interest in astronomy and microscopy extend back to when I was a youth (now in mid-sixties). But unlike microscopy it has been very much a latent practical interest, primarily because I've always lived in a typical dense British urban housing estate where there were no extensive horizons. My brother Ian and I in the past have briefly owned small reflectors and refractors but could never justify the funds invested in them for the small time they were used. Neither of us found binocular viewing satisfactory with the modest models owned and without investing in specialised models with angled eyepieces. I also have never really had the dedication to spend observing time on clear, cold winter's evenings outdoors. I do enjoy armchair astronomy, reading books on the topic and keenly watch the BBC TV offerings, especially the long running series The Sky at Night. A recent episode was devoted to urban astronomy and methods to circumvent the typical problems. This inspired me to be more proactive learning something of the night sky and how it changes during an evening and over the year despite the local limitations.

The limitations are no doubt typical of many frustrated astronomers and illustrated below. If venture into the tiny back garden the neighbour's security lights will come on even if switch our own off so would be unable to dark adapt for either visual or optical studies. The views of the sky from ground level also require more awkward high viewing angles as neighbours' properties are close by.

The view from the upstairs back and front bedroom. At the back the roof lines restrict views and also looks across to Huddersfield town centre so night glow is marked.
At the front a copse of sycamores blocks one area and both streetlights and an always-on security light centre of field are permanent light sources.

An indoor workaround - using a DSLR camera as the eyes. Astrophotography outdoors just with a camera and its lenses is of course widely practiced and if the camera is guided some outstanding images have been shared in magazines and online. From what I've read to date, indoor studies through an open window tends not to be recommended but it does have its merits for opportunistic image captures at any time a clear sky is seen. There's no need for dark adaptation or need to brave winter weather. Convenience and comfort can often dictate how often an interest is pursued.

The hot / cold air interface of an open window is not recommended for serious astronomy but at the low magnifications gives good enough images to compare with a star atlas. Viewing over rooftops is also reported to effect seeing. Security lights are not triggered from indoors and an upstairs room lowers the viewing angles required if surrounded by buildings.  In the type of urban settings that I and many others experience, making the best of the local environment still affords an enjoyable pastime.

I own a Canon 600D DSLR (APS sensor) and some fast old prime lenses (actually Nikkors for my 35 mm Nikkormat FT3 but fit and infinity focus with an adapter). The modern APS sensors have a good noise performance (albeit full frame would be better). I'm not in my case aiming for any aesthetically pleasing images but just a record shot of an area of sky, then at leisure using a star atlas or planetarium software to see what part constellations were seen and their magnitudes.

During an evening and over the year the sky seen will be sufficiently varied albeit in a small viewing area to at least gain some appreciation of the night sky. As shown below the camera can be always setup for when viewing is good. A window can be quickly opened and some images taken with no need for dark adaptation for visual studies either aided or unaided. One or more visits to the bathroom in the small hours are inevitable at my age(!) so also in a few minutes can take an image if a clear sky is spotted. In summer these are the times of course when the sky will be at its darkest.



The Canon DSLR supported on a sturdy compact tripod on a windowsill can be always ready to take images quickly through an open window either before going to bed or after. I do own an astronomy type guiding camera, the monochrome Opticstar PL-130M bought some years ago for diatom studies at the limit on a microscope but it has no tripod bush, would need a tethered laptop and find less suited for opportunistic tripod based star captures. It was more designed for attachment to a telescope. A DSLR also captures the colours of stars when marked.
The local weather apps can provide a guide as to likely clear skies. The Live View of the camera and remote ensures vibration free images with the all electronic shutter mode. The camera is pointed blind at a clear area of sky. The compass heading can be recorded and the camera angle measured either with protractor or as here with the iPhone Measure app in Spirit Level setting. These altitude/azimuth (Alt/Az) readings can be transferred to a star atlas (converting to the more commonly used Right Ascension / Declination).
Modern automatic only lenses often with no manual focus or f-stop settings are less suited for such studies. A Nikkor 50 mm f1.8 Series E is shown in use here, usually set at one stop from wide open at f2.8.



A planisphere can be handy to plan potential image capture sessions through both the back and front bedroom which point roughly SE and NW. Here 2000 GMT set on January 10th shows Orion to be just rising at the SE setting (outer red spot top right).



The 50 mm lens used acts as 75 mm on the Canon APS DSLR with a modest field of view of ca. 27º. An acetate sheet with the camera field outlined can be overlain on a suitable scaled star atlas map. The Sky Atlas 2000.0 by Tirion and Sinnott used here (largest acetate outline for this atlas, the field on the smaller scale Norton and Cambridge atlases also shown). This field can be compared with either a screen image camera capture or a printout to see what has been seen. Freeware such as Stellarium (see below) can also overlay a field of view if a DSLR sensor details and lens used are set.



Freeware such as the above web page based planetarium by Dominic Ford on his splendid in-the-sky.org website allows the lens field of view, date, time and Alt/Az to be set to compare the star field with that captured. f-Boo is highlighted mag 5.4 and this is visible on the image below. The In The Sky Planetarium software is © Dominic Ford who allows non-commercial use with thanks. The clickable star database is more limited to that of e.g. Stellarium software but find less easy to use as so many parameters. Some slightly weaker stars are also captured on good nights—stretching the RAW images shows stars to about magnitude 6.2 using the Stellarium database.  



Small crop of image using Canon 600D. 6 secs ISO 200 at 0130 GMT captured. This is near the maximum exposure to prevent star trails dependent on lens used and altitude. Guided camera mounts of both commercial and homemade designs are widely available but wish to keep the setup simple for quick opportunistic image captures. This was a SE capture over the town centre skies. To spot the weakest stars captured by the sensor some resources advise capturing a small star trail to distinguish a star from the sensor noise. The sharp eyed will notice an internal structure in some stars which may be a lens aberration.



Left. A single unguided camera image can pick out some of the brighter deep sky objects looking over the town centre sky. A crop of Orion's belt with the M42 nebula shown. 6 secs ISO 200.
Middle. Inverting the star image and printed out can be used to compare with a printed star atlas.
Right. A crop from the Sky Atlas 2000.0 by Tirion and Sinnott Plate 11 can be used to see what the dimmest stars captured were.

The astrophotography approach described still relies of course on clear skies—not too common in the north of England where I live! Good planetarium software can supplement such studies to watch how the skies will change over an evening and during the year and also allowing future imaging sessions to be planned. The open source Stellarium planetarium freeware is noted for one of the most realistic looking sky views and can take into account likely light levels limiting views in the location entered. I'm currently awaiting a clear sky to try and capture the Andromeda galaxy on the few occasions that it clears the copse of sycamores shown above. There are planetarium phone apps that change the sky view depending on location and compass bearing but do not find these small screen views very practical indoors.

These are admittedly opportunistic and very basic attempts to learn aspects of the night sky in indoor comfort with equipment already owned rather than braving the cold nights at times when I prefer to be tucked up in bed! There are telescopes that can be set up outside and controlled from the comfort of indoors but cannot justify investing in such optics for the relatively few times that conditions are suitable. This particular approach also combines some interests—the use of older prime camera lenses, star atlases at various scales and planispheres.

Comments to the author David Walker are welcomed.

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