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


Croydon Astronomical Society
est. 1956

Observing with the Croydon Astronomical Society

Members of the society carry out observations at both the society observatory at Kenley as well as a wide range of locations, in Croydon, other parts of the UK and abroad.

In addition to visual observing members record their observations on a variety of instruments including film cameras, CCDs, standard digital cameras and video.

Current favourable objects tonight. Rather than repeat identical information already in numerous other places, the links below give information on what is visible in the night sky right now:

















   For daytime, the Sun



Observing Projects

The following are some ideas for events and objects to observe. The lists also contains both short term and longer projects that may be of interest to members and others. If you take part in these projects let us know via our forum croydonastro. Your results can be presented at our Annual Exhibition Meeting.

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





Venus Express Ground Observing Project

The Venus Express Ground Observing Project (VEXGOP) is an opportunity to contribute scientifically useful images and data to compliment the Venus Express (VEX) spacecraft observations of Venus. The project will focus on utilising the capabilities of advanced amateurs to obtain images of the atmosphere of Venus; specifically filtered monochrome images obtained with CCD based cameras in the 350nm to 1000nm (near ultraviolet, visible and near infrared range).

The Venus Express (VEX) spacecraft will observe the planet Venus using seven instruments for at least two Venusian years (1000 days) beginning in May 2006. The instrument package includes the Venus Imaging Camera (VMC), which will image the planet in the near-UV, visible and near-IR range. Although VMC will provide much higher resolution images of the planet than visible from Earth, continuous monitoring of the planet will not be possible.

There may be periods, therefore, when parts of the planet are visible from Earth that are not visible from the spacecraft (due to the spacecraft position in orbit). Additionally it is important to compare Earth-based observations with simultaneous spacecraft observations. In particular this will allow us to extend our understanding of the dynamics of Venus’s atmosphere based on the VEX data to observations made prior to the VEX mission, as well as after completion of VEX operations. Objectives

The objectives of VEXGOP is to obtain high quality images of Venus before, after and during VEX operations. Amateur astronomers, using CCD based cameras with filters for specific band passes in the near ultra-violet, visible and near infrared wavelengths (350nm to 1000nm), are encouraged to participate in the gathering of images. Observation campaigns will include:

    * Routine images of Venus during each apparition

    * Coordinated observations during specific periods of the VEX mission to provide either simultaneous or complimentary ground based images to VEX spacecraft observations

For more details go to:


May 2006

to at least


Asteroid 10381 Malinsmith

Image the asteroid 10381 Malinsmith and win a prize

Konrad Malin-Smith, a life member and past chairman of the Croydon Astronomical Society, has an asteroid (minor planet) named after him, 10381 Malinsmith. It was discovered on 3rd September 1996 by Brian G.W. Manning at Stakenbridge.

The challenge is for members to acquire at least two image of the asteroid. A small (unspecified) prize is offered to the first member to produce two images showing the motion of this asteroid and also provide supporting evidence to prove that the asteroid observed is 10381 Malinsmith. This evidence is to be presented to the members of the society in the form of a short talk at one of our meetings.

More details are on this page 10381 Malinsmith, which also generates an ephemeris (table giving the position of this asteroid in the sky at the current time) to allow you to point your telescope in the right direction to image it. In addition it shows a very nice animated diagram of its position in relation to the solar system.

Until the Prize

is Won

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.

The Transit of Venus on 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.

The Transit of Mercury on 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.

The Eye - your key to observing the Universe

The eye is a vital tool to detect photons that come through a telescope - coupled with the brain it is a very sophisticated detector that interacts with the image in subtle ways. To understand how to get the best from your personal detector you need to understand how the eye brain system functions. One place to look is The Joy of Visual Perception: A Web Book. This ‘book’ also contains an extensive list of links to other sites dealing with human vision.

You may also like to read Eye and Brain, The psychology of Seeing by Richard L Gregory, Oxford University Press {ISBN 0 19 852412} and Chapters 1,2 and 3 of Visual Astronomy of the Deep Sky by Roger N Clark, Cambridge University Press {ISBN 0 521 36155 9}.


Telescopes for Amateur Astronomers

A wide variety of telescopes are available for amateur astronomers., in April 2002 we held a special meeting dedicated to showing our members some of the many types available. The calculations described in this presentation are programmed in an Excel 97 spreadsheet that enables you to calculate the performance of a telescope given two of the basic parameters – diameter, focal length or focal ratio.

This is available below - try it and see if it is useful. This also calculates the parameters if you have a CCD camera attached to the telescope.

21st April 2003 The calculation spreadsheet has been updated it now allows you to select the camera you are using from the supplied list and copies the details into the calculation sheet rather than you having to do the copying manually. If you have a camera that is not on the list you can enter the details in the User Section. You should also be able to calculate the FoV and other CCD details for standard camera lenses if you use these on your CCD - just enter the focal length and the f/number in the telescope sheet.


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 ! -


To ensure that the results are useful we need to ensure that the correct time is recorded. Our page Science at the CAS: Observation Time will allow you to set your clocks and lead you to definitions of the different flavours of time.


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 visual observation very difficult. Additional information on light pollution may be found on our light pollution page. 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.


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