Observation by Martin Butcher: M48 - An open star cluster

Uploaded by

Stuart Morris

Observer

Martin Butcher

Observed

2012 Dec 11 - 05:02

Uploaded

2021 Apr 06 - 17:59

Objects

M48

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Constellation

Hydra

Field centre

RA: 08^h13^m
Dec: -05°47'
Position angle: +1°09'

Field size

1°01' × 0°41'

Equipment

Meade LX-90 8" telescope fitted to its field tripod by an equatorial wedge.
LX-90 Periodic Error Correction enabled.
Dew Removal straps fitted to telescope and camera lens
Telescope and camera powered by Mains Power.
Stock Canon 40D with 200mm f/2.8 lens stopped down to f/4
Telescope driven but unguided

Exposure

Thirty sub-exposures each 30 seconds taken at ISO800

Location

Isle of Colonsay

Target name

M48

Title

M48 - An open star cluster

About this image

M48 is an open star cluster located in the constellation Hydra.

Equipment used:- Stock Canon 40D mounted at Prime Focus on Meade LX-90 8” telescope (focal ratio f/10 focal length 2,000mm) with a 0.63x Focal Reducer (giving an effective focal ratio of f/6.3 and focal length of 1,279mm) fitted to its field tripod by an equatorial wedge. Telescope Polar Aligned. LX-90 Periodic Error Correction enabled. Dew Removal straps fitted to telescope and operating. Telescope driven but unguided. Telescope and camera powered by Mains Power.

Exposure details:- Thirty sub-exposures each 30 seconds taken at ISO800. Ambient temperature minus 7 degrees Celsius.

Processing details:- After quality control 7 sub-exposures calibrated with Dark, Flat-field and Bias Master frames before being combined and processed in Images Plus. Image rotated in Photoshop CS5 so that North is at the top and cropped to give field of view 45 arc minutes x 30 arc minutes.

Narrative description:- Twenty seven days after New Moon, the Moon had not risen before imaging completed. The weather was calm, clear and very cold with a heavy frost. Although at the time I believed that I had achieved an accurate polar alignment I now doubt this, as on inspection there was much star trailing and many sub-exposures had to be discarded.

Files associated with this observation

MButcherNGCNGC2548 or M48.jpg (152.0 kB)

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