Occultation of BY Cancri (SAO 98054) by Saturn and its ring system

25th January 2006 (18h 05 UT - 20h 50m UT)

Observers' Reports

This event took place on the evening of Wednesday, 25th January, a few days before Saturn's 2006 opposition. SAO 98054, at m(v) 7.9 was a little brighter than Titan. The occultation presented an interesting challenge for amateur observers. It is of course reasonably rare for a star of this magnitude to be occulted by the Saturnian System. Click here for the full details published prior to the occultation.

Observers in the UK and in Bucharest, Romania, were successful in obtaining images and sketches of the event at various stages, and their reports are as follows:

Phil Denyer - Hornchurch, Essex

This was my first observation of an occultation with the intention to try and confirm some timings. I was using a 254mm dobsonian at 179x magnification. Unfortunately I am not equipped to do any imaging. I managed to observe the occultation without clouds, although the seeing was not very good and any thoughts of getting accurate timings did not seem likely. The following was the best that I could achieve:

• 18h 38m I could make out the star very near to the rings.
• 18h 43m I could no longer distinguish the star from the rings. I was not able to see the star passing through the Cassini Division.
• 20h 54m 24s In a brief glimpse of steady image I noticed a very slight protrusion to the edge of Saturn's disc at the expected point of reappearance.
• 21h 06m I could confirm that the image of the star was clear of Saturn's disc.

I don't know if my results could be of any use to you, but I certainly enjoyed being a witness to the event.

Alan Heath - Long Eaton, Nottingham

Alan is an accomplished observer of Saturn and has made some fine observational notes to accompany his excellent sketches of the event, observed from his home at Long Eaton, Nottingham, using a 10-in (250mm) Reflector.

The beginning of this occultation could not be seen due to obscuration by trees.

• 18-30 UT Still tree obstruction but I could get an image of Saturn but it was so bad I could not see the Cassini Division. Cloud prevented further observation.
• 20-00 UT A bright spot seen in Ring B1 adjoining the globe which I took to be the Terby Spot but later realised it may have been the star which was predicted to be in this position at the time.
• 21-00 UT Star seen adjoining the limb of Saturn on the following side of the SFR. At this time I found the Terby Spot uncertain so perhaps it was the star seen at 20-00.
• 21-02 UT Star well seen just off the limb.
• 21-07 UT Star seen well clear of the globe.
• The magnitude of the star was about equal to Rhea, which proceeded the planet by about two ring diameters. Rhea is visual magnitude 9.7. I could not see Enceladus which was just off the SPR but Enceladus is magnitude 11.7. Seeing at this time was S3 end Tethys was seen also.

It had been hoped that BY Cancri might have been seen as it passed through Cassini's Division but cloud prevented seeing this. Unfortunately only the re-appearance of the star was observed at 21.00 UT, which is the predicted time.

John Smith

I've done a few sketches and thought I'd send this in. I made the drawing first (without any reference to planetaria software!) and drew the moons/stars in with size proportional to my perceived magnitude. Titan, Rhea and BY Cancri fit OK with what I later saw on Starry Night and Redshift, but the other star (at about 4 o'clock) was meant to be only as bright as Rhea (9.4), whereas I drew it and distinctly remember it as being the brightest of the 4 objects near Saturn by far.

My original pencil drawing was scanned into Photoshop, inverted and then tidied up (stars/moons made into circles and Saturn coloured as near the yellow I remembered).