Sets of New Flat Frames were acquired on 2026-07-10 using Light Board placed in front of the LX200.  This was necessiatated by movement of dust on the front of the SBIG Camera window (change in dust mottes seems to affect other filters besides the C Filter).    Only a subset of filter/bin combinations were acquired requiring new combinations to be acquired sometime before start of main observing season.

Flat Frames

Flat frames were acquired for two binning modes  for C filters (3x3, 2x2) and one binning mode for B, V, R filters (3x3) with CCD Temperature operating at +5°C as per the following table:

Filter

Filter

3x3

2x2

1x1

Position

Name

n

Exp(s).

Sheets

n

Exp(s)

Sheets

n

exp(s)

Sheets

1

C

21

x

2s

(2)

21

x

3s

(2)

None

2

B

19

x

3s

(1)

None

None

3

V

19

x

3s

(2)

None

None

4

R

19

x

2s

(2)

None

None

-

Dark Frames

Dark frames were acquired with CCD Temperature operating at the same value of +5°C that the flat frames were acquired at.

3x3				21	x	2s
3x3				21	x	3s
2x2				21	x	2s
2x2				21	x	3s
1x1						None

Master Frames

For each Dark Set the Dark Frames were stacked using AvMedian method in the Sigma Beta program. The Master Bias & Master Dark Frames generated were copied to the relevant subfolder (1x1 Masters, 2x2 Masters & 3x3 Masters) at 'C:\Data\CCD Imaging\Analysis\_Darks\+5c'

For each Flat Set the Flat Frames were reduced in CCDSoft using the Reduce Folder facility using the Flat Frame Reduction group and relevant master Dark and Master Bias Frames. Reduced flats from each set were then stacked using AvMedian method in Sigma Beta program. The Master Flats generated were copied to the relevant subfolder (2x2 Masters & 3x3 Masters) at 'C:\Data\CCD Imaging\Analysis\_Flats'

Pictures below show the newly generated Master Flats for the C Filter, and are compared with the previous Master Flats.
The movement of one or two of the dust mottes on left hand side can clearly be seen.

New Master Flat, C filter (3x3) from S1438 (Average Median for 21 frames, 2026-07-10 )
Previous Master Flat, C filter (3x3) from S1361 (Average Median for 23 frames, 2025-09-12 )		Earlier Master Flat, C filter (3x3) from S1347 (Average Median for 25 frames, 2025-08-13 )