CREATOR: XV Version 3.10a  Rev: 12/29/94  Quality = 75, Smoothing = 0
Observational Lab
with the Bengt Westerlund
Telescope (BWT)

 

 

 

 

Goals

Take images of bright galaxies in three filters.

 

Strategy

Try to achieve the best dynamic range by adjusting the exposure time with each filter.

 

Calibrations

a)    Take calibration frames for the dark current at different exposure times and derive bias level and dark current rate. Keep track of temperature of the CCD.

b)   Take flat fields using the same derotator position as for the targets (see below).
Hint: if the same derotator position is used for all targets and filters than a single set of flat fields can be used for all observations.

 

Targets

a)    Go to the first object, make sure you are there and note the current ART angle in AutoSled (Angle of the camera mount Relative to the Telescope).

b)   Take images (longer than 5 minute exposures require the use of offset guider) in the first filter.

c)   Move back the derotator to the initial ART value. Take next filter images.

d)   Repeat c) for the last filter.

e)    Go to next object, return the derotator in the initial position and repeat steps b), c) and d).

 

Questions and topics to include in the report

a)    What was the level of bias and dark current derived and how did you do it?

b)   How did you combine flat field exposures?

c)   What was the signal-to-noise ratio in the combined (master) flat?

d)   How did you determine the dynamic range of the target images?

e)    What was the limiting factor for the length of a single exposure?

f)    How does the optimal exposure time depend on the filter and why?

g)   Present images.

 

List of targets

The table below contains a list of galaxies that can be observed in the evening during the winter. Columns give name in Messier catalogue, coordinates (2000 epoch), hour (local time) from which observations can be carried out, angular diameter (arcmin) and B magnitude.

 

Target

a

d

Time

Size in arseconds

Bmag

M110

00

40

22.00

+41

41

07.0

18

18.62

x

11.48

9.4

M32

00

42

41.87

+40

51

57.2

18

9.12

x

6.61

9.2

M74

01

36

41.84

+15

46

59.6

18

10.47

x

9.55

10.5

M81

09

55

33.17

+69

03

55.1

18

22.38

x

11.48

8.1

M82

09

55

52.19

+69

40

48.8

18

10.47

x

4.36

9.2

M108

11

11

31.29

+55

40

31.0

20

8.13

x

2.75

10.7

M109

11

57

35.90

+53

22

35.0

20

7.08

x

4.57

10.7

M106

12

18

57.54

+47

18

14.3

22

16.98

x

6.46

9.6

M94

12

50

52.63

+41

07

09.3

23

12.58

x

10.96

8.7

M63

13

15

49.28

+42

01

46.5

23

13.18

x

7.94

9.7

M51

13

29

52.37

+47

11

40.8

23

8.32

x

7.08

8.8

M102

15

06

29.48

+55

45

47.2

23

6.46

x

3.16

11.1

 

Target assignment

 

Kjell Rosengren

 

Björn Eckerbom                   

M81 eller M82

Sascha Kulas

 

Andreas Lundin

 

Vibeke Moving

 

Mattia Levi

 

Erik Aronson

 

Tuomas Mattson

 

Izabel Roca Vich

 

Sergio Velasco

M109