Following the talk that we had recently on satellite communication, I came across an article on from the European Space Agency on space debris. I thought you might be interested in some of the findings. The US Surveillance Network is using ground based radar, optical and infra red sensors to track 7500 objects. The minimum size of a trackable object is about 10 cm for a low earth orbit, and 1 m for a geostationary orbit. Only about 60% of these are active satellites. Over 40% are fragments of disintegrated satellites and upper stages of rockets. The vast majority of man made objects in orbit are smaller than 10 cm which are not trackable.Estimates of objects larger than 1 cm range from 30 000 to 100 000.

The main hazard of space debris iscollision, but space is very big and the current risk level is small butsteadily increasing, and expensive shielding may become necessary in the future. Current practices aim at reducing the growth rate, but the amount of debris is still rising, as the natural removal by atmospheric braking and re-entry is exceeded by the deposition of new material. Space debris is an international problem and requires international co-operation if the problem is to diminish. Improvement in radar techniques and the upgrading of a 1 m optical telescope on Mount Teide, Tenerife, in order to improve the detection rate are currently in hand. Spacecraft returned to earth from orbit show considerable impact damage, although it is difficult to know if the damage was caused by space debris or meteoroids. Both NASA and ESA are actively pursuing research programmes aimed at producing models and detection procedures that will quantify the problem.

Geoffrey Johnstone

Sometime just a little ingenuity and time will repay dividends when trying to observe deep sky objects

Being new to astronomy, I found that star hopping was a some what difficult task as I was always getting lost and having to start all over again from my original position. On one occasion I was looking at Alphard in Hydra and tried to star hop over to M48. I ended up with Sirius in the field of view. I looked at the setting circles on a friends equatorial mount and began to think if these could be attached to my 60mm refractor altazimuth. It seemed that the RA would be the same but the Dec would be out only after a couple of degrees of RA. Anyway, I got hold of a protractor and marked off the 360° marks on a circle. Each mark being 4 minutes in RA, larger marks for the 20 minute intervals and an even larger mark for the hour interval. A second circle was drawn up and this time only 180° was used. This gave me +90° for the north pole, 0° at the equator through to -90° at the south pole (you?ll be lucky from this latitude). Both circles were cut out and stuck to thin cardboard, holes were cut in the centre for mounting purposes. The RA circle was put on the left to right mounting on the tripod. A paper clip was bent and cut to size and fixed with Blu-tack to the rotational part of the azimuth mounting.

This hopefully would not be too far out. On the sides of the telescope there are two fixing screws, the left hand one was undone and the Dec circle was placed here and the screw replaced. Again a paper clip was fashioned to make a pointer and Blu-tack used to fix the pointer to the telescope. 3 nights later I was able to use the new circles. Firstly I centred Sirius in the eye piece, set the circles to their respective RA and Dec. Looked up the co-ordinates for M50 in Monoceros and moved the telescope to the RA / Dec listed. To my great surprise and relief, M50 was in the field of view. OK, next! Centre Alphard in Hydra, set the circles and move to M48 on the border of Hydra and Monoceros. Nothing there, the RA was only 4 minutes out but the Dec was some 5° out. The answer was to find a star very close to the object that I wished to observe, set the circles, then move the telescope to the co-ordinates. If the object is not in the field of view then move only in declination first. If the desired object was higher in the night sky than the original co-ordinates then slowly raise the Dec, move the telescope downwards if the opposite was true.

How many of us can remember back to when on frosty winters nights, skies where dark with countless stars shining down and the Milky Way was a river of light across the sky?

May I bring to your attention a growing problem through out the country that I believe needs to be addressed as soon as possible, that is, the growing menace of the bright lights syndrome. You may already be aware that sky glow is caused by dust and moisture particles illuminated by unguarded lighting seeping into the night skies, thus causing the horrible glow over our cities. Quite a lot of street lighting is wasted by going upwards into the night sky, whereas all the light is needed down near the ground. This could easily be achieved by fitting better reflectors , hoods, shrouds and/or skirts. Thus directing the light downwards, with this done maybe a smaller wattage light (tube or blub) could be used. This would cause less dazzle and be cheaper to run.

I am not suggesting for a moment that all lighting should be switched off as that would be foolish to say the least. The security lighting that can be bought relatively cheaply from the high street are becoming more common in back gardens etc. These could be fitted with passive infra-red, heat and/or motion sensors to detect/deter any anti-social elements on the prowl. If security lighting must remain on during the hours of darkness simply by directing the light below the horizontal would help. Astronomers lighting needs are the same as everyone else?s, we are not a special breed that shy away if caught in bright lights. What we really are, are ordinary people with a hobby or past time that takes us out side during the hours of darkness to gaze at the wonders of the cosmos. Do you realise that the light from the nearest star has taken over four years to reach us, so really we are looking at history unfolding.

The reason for my writing is an article in the magazine Astronomy Now, July 1994 issue, pages 18-20. I believe the article speaks for itself, especially the picture on page 19, showing England and Europe lit up like a Christmas tree during the hours of darkness. I am an amateur astronomer who enjoys the company of the stars, but, because my hobby takes me out side during the hours of darkness to observe the richness of the cosmos only to find the night skies an orange colour and most of the faint glories beyond my grasp. I am not the only one suffering this problem, in fact most, if not all, amateur astronomers do suffer this problem. The natural resources of our planet will not last forever, so is it not logical to conserve them now.

What I mean is the fossil fuels with which each of us use to warm our homes, cook with and light our surroundings when needed. My point being is; in 1992 Britain spent £150 M operating 5.5 million street lights and as much as £40 M was wasted lighting up the night sky! May I bring to your attention the Campaign for Dark Skies (CfDS) who are trying to save our night skies now before it is too late and our childrens children miss out on the glories to be seen. If you are so disposed, would you add your voice to ours in asking the people who matter to act NOW. As of November 1994 there was a petition with the Petitions Committee within the European Parliament. Write to your MEP and ask them to sign it so as to reduce the light emitted upwards from unguarded lighting. Write to your local MP asking him/her to take up the fight to cut down un-necessary illuminating of the night skies. Also write to your local Councillor asking him/her to also help cut un-necessary light intrusion.

A variable star arguable the most dynamic for amateurs with small telescopes to observe, as its cycle from mag. 7.9 to 7.2 and return takes roughly 4 hours, and so the event can be witnessed during one observing session. VZ will always appear fainter than the star 36 Cancri at 6.5 mag., however, 37 Cancri at magnitude 7.4 makes an excellent comparison for CZ. VZ Cancri is a RR Lyrae type variable star the interior of which are rather unstable going through a cycle of heating -expanding- and cooling -contracting- all in a bit over 4 hours. Note the detail chart to identify VZ is shown north upwards so when a telescope is used to search for the variable star turn the chart upside down. Whilst in the vicinity of CZ Cancri take a look at M67 appearing as a grainy haze of light in small telescopes but really consisting of 500 member stars most of which are extremely old and evolved into red giants and from this its estimated to be one of the oldest open clusters known with an age of 5 to 10 billion years. The cluster diameter is approximately 10 light years across and lies at about 2,500 light years away. The integrated visual brightness of the cluster is made up of stars ranging from 8.5 to 15^th magnitude and fainter making it only 6.1 mag. - just at the limit of naked eye visibility, however through a 6" telescope with a magnification of 40x the cluster becomes a splendid object.

It is possible to see meteors on most clear moonless night?s, but on some nights of the year they are much more abundent. This is when the Earth?s orbit intersects a trail of meteoric dust orbiting the Sun. If the dust is well spread out, a shower can last for several days. Meteor?s will be seen to radiate from a point in the sky and from a particular constellation. The following table gives details of the more easily observed meteor showers.

Date                      Shower Max             R.A.(h.m) Dec(deg.)

Jan 1-4                  Quadrantids Jan 4          15:28 +50
April 20-22            Lyrids Apr 21               18:08 +32
May 1-8                Aquarids May 5             22:20 0
June 17-26            Ophiuchids June 20        17:20 -20
July 15 to Aug 15   Delta Aquarids July 29   22:36 -17
July 15 to Aug 20   Piscis Australids July 31 22:40 -30
July 15 to Aug 25   Capricornids Aug 2       20:36 -10
July 27 to Aug 17   Perseids Aug 12              3:04 +58
Oct 15-25              Orionids Oct 22              6:24 +15
Oct 26 to Nov 16   Taurids Nov 3                3:44 +14
Nov 15-19             Leonids Nov 17           10:08 +22
Dec 9-14               Geminids Dec 13            7:28 +32
Dec 17-24             Ursids Dec 23              14:28 +7