Comet C/2004 Q2 (Machholz) - Final Photo Call?

Dia 1: A diagramatic view of the field around comet Machholz (2005 April 02, 00h 20m). Stars to magnitude 11.5 are shown.

Dia 2: Track of Comet Machholz from April 4 to May 4 2005, shown in black and white for clarity. Positions are for zero hrs of date.

Dia 3: A wide field diagram showing Comet Machholz in relation to neighbouring stars as at 22h 00m April 04 2005.

The above from SkyMap software by Chris Marriott to whom I am indebted.

Fig 1 Comet Machholz imaged April 02 2005 at 00h 20m. A 60 sec exposure ISA 350 160mm f/1.8, guided camera.

Fig 2 Comet Machholz imaged April 02 2005 at 21h 43m. The comet is close to the star TYC 4549-1208-1, magnitude 9.2. A 60 sec exposure ISA 350 160mm f/1.8, guided camera.

Comet Maccholz is now headed for the Plough (Dia 2).

At magnitude 8.5 it is still observable in 8x30 binoculars as a small, fuzzy patch - provided you know exactly where to look for it. (A large field view is shown in Dia 3)

Machholz therefore continues to be the preserve of northern observers.

From the Northern Isles it passes close to the zenith between 22h and midnight (UT) but a dark, clear sky is essential.

The comet was imaged from Rousay in the very early hours of April 2 and again some 21 hours later. It still looks surprisingly "large" (relatively speaking) in 7x50 binoculars.

However, with rapidly encroaching twilight (astronomical twilight lasts all night here from 25 April to 18 August) and diminishing brightness, it is unlikely to be visible with small instruments for more than a further ten days. Thereafter the Moon also enters the scene.

Machholz represents something of a record for me personally.

I have observed comets now for more than half a century but at no time have I had one particular comet under scrutiny for such a long period as with Machholz.

Having first observed it on Christmas night 2004, I have over four hundred images snatched between some of the worst winter observing conditions I have experienced anywhere.

Fig 2 shows the most recent photograph (approximately 6° x 6°).

For identification, compare this to a computer programme of the same part of the sky (Dia 1). Note the beautiful grouping of stars towards the top left margin. Stars to magnitude 12 are visible in the photograph.

The brightest star in the field (mid-right) is TYC 4542-2796-1, magnitude 4.9.

Fig 1 shows the same field 21h 20m earlier. Note the difference in sky quality.

This earlier photograph was taken following a day in which high cirrus had been seeded by aircraft trails.

The comet has dropped in declination by 0.5°, approximately the Moon's apparent diameter.

JV 03/04/05