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© Croydon Astronomical Society 2012 Croydon, Surrey, England, UK Registered Charity No. 251560


Croydon Astronomical Society
est. 1956

Members of the society carry out observations at both the society observatory at Kenley as well as back gardens, in the local area of Croydon, nearby and other parts of the UK and abroad.

In addition to visual observing members can record their observations on a variety of instruments including cameras, both still and video.

Current favourable objects tonight. Rather than repeat identical information already in numerous other places, a selection of links below give information on what is visible in the night sky, right now and in the months to come, as well as general observing and amateur astronomy information. These links are reviewed regularly:




















   For daytime, the Sun



Most if not all of these websites have much more interesting and useful information astronomically and are recommended to be explored.

Observing Projects

An excellent way to be motivated and involve fellow members is to think of and engage in an observing project. If anyone has something particular in mind please mention it via our forum croydonastro. Fellow members who would otherwise not engage would be willing to give advice. Your results can be presented at one of our society meetings if you so wish.

New projects or events will be added to the top of this list and some will be archived after the event.

More details of our observatory can be found here.

Members images are shown in the gallery.

To enable you to plan your observing sessions this website shows the twilight times for London.

Transit of Mercury, 9th May 2016

Transits of this planet occurr far more frequently that those of Venus (the last two for Venus was 2004 and 2012 and the next is now 2017 and 2125). The next transit of Mercury is now fairly close, 9th May this year and we hope to open our observatory at Kenely to view this, Monday from midday towards sunset.

Transit of Venus, 6th June 2012

The European Southern Observatory has a page of information on both transits - they are intending to try to determine the size of the Earth’s Orbit from these measurements. This was used as the historic method of measuring the size of the Solar System but has now been superseeded by radar measurements. It should still be interesting to see how accurate the measurements are.

Transit of Mercury, 7th May 2003

To aid planning your observations here in PDF format is a list of the altitude and azimuth of both the Sun and Mercury for the Transit for our Observatory at Kenley. Note that the Sun is very low around 6 degrees at First Contact. Also its azimuth is 70 degrees so you need a site with a clear north east horizon to get a good view or better still take a video. In both cases you must not look at the Sun directly or with any optical instruments unless you have taken proper precautions.


Telescopes for Astronomy

A wide variety of telescopes are available, from beginners to serious amateur astronomers and the choice can be bewildering, especially so for people new to astronomy and optical equipment. Whilst it’s true that all telescopes do essentially the same thing, after some expereince and practice - and knowing more about each type of telescope - many people in hindsight would have bought something else. This is the case even with experienced observers, as they may specialise in a particular astronomical object. Often it can be a case of buying something bigger and or better (expense now justified), but the type and size of telescope is such that careful thought is required before even the first purchase.

It would be simple to list a few websites where good advice is given, instead the current advice would be to do a simple Internet search, say on: ‘choosing telescope’. The reason being that they are all good and very similar. It would otherwise be what would be done here anyway.

If you come across a good website do please mention (webmaster) and it will be listed here, thank you.



For those already with equipment, or looking for a particular telescope, or telescope-camera combination, these website provide online calculators where you enter simple measurements and it produces useful information. An example would be the field of view obtained with a telescope and/or camera combination:






For those with Dobsonian and other alt-az telescopes, knowing where to point the telescope is not obvious, but the following calculator converts a celestial co-ordinate from the RA and Dec to altitude and azimuth. RA and Dec are the celestial equivalents of terrestrial Latitude and Longitude:


Alternatively for those with an Android mobile handset there is SkEye, a planetarium type app which in addition to many features has a continuous readout of both RA and Dec and the Alt-Az equivalent. There is also the feauture that it can be attached to your telescope in any position and it tells you where to point the telescope to find a particular object.


Observing Logs

Serious observers need to record their results so that they can be analysed later or for the less serious observers we need accurate notes to jog our memory:


If you have a CCD camera and are interested in contributing vital observations of variable stars the American Association of Variable Star Observers have a useful manual here that will tell you how to make measurements that will be useful to professional astronomers. If you submit any observations please let us know.


One of our concerns is the ever increasing level of light pollution which is making observing more difficult. To allow the effects of light pollution to be recorded and assessed we are trying to develop a standardized means of photographing the night sky so that we can compare the levels of light pollution at different sites and try to monitor any changes.


Observing with the Society (highlights of current objects below)

There are a couple of comets in the sky right now, certainly visible via binoculars, and if we are lucky a naked eye one.


This short period comet is expected to reach closest approach in early 2017 at a distance of 0.08 au. The comet has brightened rapidly and it re-emerges in the Northern hemisphere in February. Throughout February 2017 it is expected to reach magnitude 6 covering plenty of ground as it moves rapidly through Capricornus, Aquilla, Hercules, Corona Borealis, Bootes, Coma Berenices and Leo where it will remain throughout March. By this time it will have faded to around magnitude 10 unless anything unexpected happens.


Another short period comet is expected to reach magnitude 5 in the spring of 2017 bringing it within naked eye visibility. With a nucleus of an estimated 1.4 kilometers in diameter and a reputation for flaring, this comet reaches perihelion at the end of March. Well placed for northern sky observers from January until June, this comet will be a treat for binocular observers from March and may enter the realm of naked eye visibility in dark skies. A notable photographic opportunity arises at the end of April when the comet passes within 5 degrees of Globular Cluster M92.


Venus has now passed in front of the Sun and is a morning star, still close to the Sun but getting easier to see with every passing day at dawn. Mars is close to the Sun in the eveming sky but getting lower, fainter and orange; Jupiter is very bright and now rises before 8 pm.


See the Moon phase at the top right of most of these webpages.

Highlights of current objects

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