Sunspot data

Sunspot data is available for the following periods:

2023Q4 2023Q3 2023Q2 2023Q1
2022Q4 2022Q3 2022Q2 2022Q1
2021Q4 2021Q3 2021Q2 2021Q1

The data presented in this section of is collected for Leif Svalgaard's Solar Observing Project: Re-calibrating Historical Sunspot Observations of the AAVSO. Data is collected by projecting the Sun on a paper sheet using a 60mm diameter 1490mm focal length Galilean Type Telescope (GTT60), stopped down to 30mm diameter (f/50), and equipped with a 24mm diameter, -75mm focal length, plano-concave eyepiece (20x magnification).

Using pencil the visible sunspots are drawn onto the paper, which then is scanned and uploaded to this site together with an image of the Sun taken shortly after the sketch was made using a SkyWatcher Esprit 150ED apochromatic refractor.

30 August 2023Recording groups and Wolf-numbers for SILSO onto the drawings (totals and for northern hemisphere, southern hemisphere and central 50% region).
29 August 2023First entry into the SILSO-database.
3 June 2023New construction of the drawing table to ensure proper orientation of the drawing.
26 May 2023The rotational error was mitigated, but still not stable.
14 May 2023An accidental but significant rotational error was introduced to the drawing table.
10 April 2023Images are now only taken using the ZWO 82nm bandpass green filter.
19 January 2023Started taking solar images both using luminance and a ZWO 82nm bandpass green filter.
28 July 2022Started recording minimum seeing (in arc-seconds) as an indication of image quality.
19 April 2022Solar images are now processed both without and with sharpening (with 30% raw blend).
23 February 2022Continued observing after delayed return of the mount.
2 November 2021Temporarily stopped observing as the mount was shipped to Italy for maintenance.
3 September 2021Started recording camera exposure times (in ms) and average seeing (in arc-seconds as measured with a Solar Scintillation Seeing Monitor) as an indication of transparancy and image quality.
25 April 2021Stopped counting groups on request of Leif Svalgaard.
28 March 2021Introduced pre-printed diagram with 80mm diameter solar disc circle.
25 March 2021Switched to -75mm focal length (20x) eyepiece. Standardised the projection to 80mm diameter.
23 March 2021Stopped down the objective to 30mm (f/50).
22 March 2021Switched to -150mm focal length (10x) eyepiece, but still full aperture.
14 March 2021Second observation, now only with -200mm focal length (7.5x) eyepiece, still using full 60mm aperture. This method is now used daily.
6 March 2021First observation with two different eyepieces of -200mm (7.5x magnification) and -37mm focal length (40x) and full 60mm (f/25) aperture. Imaging straight after the observation with a SkyWatcher Esprit 150ED (150mm aperture, f/7, with ZWO field flattener) using ND5.0 foil filter, ZWO luminance filter (approximately 385 - 695nm bandpass at FWHM) and ZWO ASI1600MM Pro Cool camera. The images are the result of 30s video in which 230 frames are shot, 10% of which are stacked using AutoStakkert

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