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Hemispheric information (ng, sg, ns, ss, cg, cs) ?

maxsurlaroute
Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 02/11/2021 - 01:47

Hello,
When completing an observation report in SunEntry Program, it is mentioned that we can optionally add the "hemispheric information (ng, sg, ns, ss, cg, cs)". What does each of the terms precisely mean: ng, sg, ns, ss, cg and cs?

Thanks in advance and have a good day,

Max

Thu, 02/11/2021 - 12:44
ng, sg, ns, ss, cg, cs

Hi Max,

If you know exactly where the north and south hemisphere are during each day of the year (the sun turns as we rotate around the sun) then ng is the number of groups in the north hemisphere, ns the number sunspots in those groups, sg the number of groups in the south hemisphere and ss the number of sunspots in those southern groups.  You should look at the StonyBrook disk (Spotplot.exe may not work on new windows machines now;  https://www.aavso.org/solar-software )  and the time of year to see how those North and South hemisphere orientations are for the daily observations, mostly the StonyHurst disk is for those folks who use the projection method of observing the sun: 

Here's some good software to get the idea:  http://www.petermeadows.com/html/software.html

The cg and cs are at the center of the sun for counts of groups and sunspots. 

Rodney

 

maxsurlaroute
Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 02/13/2021 - 03:20
Central solar zone

Hi Rodney,

Thank you very much for these details as well as for the software which corresponds exactly to my need.

One last thing, for the cg and cs codes what is the convention for determining the central solar zone?   For example, is it a central strip whose width corresponds to the central solar latitude 0 ° ± 10 ° (10 ° North and 10 ° South)?

Have a nice day,

Max

Sat, 02/13/2021 - 13:39
cg, cs

Hi Max,

I looked for a definition of cg and cs in Peter Taylor's book 'Observing the Sun', but he does not identify what that is. In fact he does not even mention the center groups or sunspots. He shows how to record the North and South hemisphere groups and sunspots the way Peter Meadows does, but nothing about the center radius.  

I know some observers estimate the center, perhaps about 1/3 the radius of the sun? Perhaps there are other folks who have a definition and might comment. 

Rodney

 

 

maxsurlaroute
Affiliation
American Association of Variable Star Observers (AAVSO)
Sat, 02/20/2021 - 19:44
Differential rotation ... more and more interesting

Hi Rodney,


Thank you very much for looking for answers to my questions.


For my part, after several readings and reflections here is where I am :

  • Mr. Richard Christopher Carrington, discoverer in 1863 of the differential rotation of the Sun and generally credited with the discovery of Spörer's (Gustav) law, which describes the variation of the latitude of sunspots during a solar cycle, summarizes his theory as follows. on the sunspot cycle:
    • “A little before the minimum there are only spots near the solar equator between plus 5 and minus 5 from this moment the spots suddenly appear at high latitudes towards plus and minus 30 then they multiply between these limits, and, when the maximum is reached, their mean latitude constantly decreases to a new minimum ... "
    • In addition, Mr. Gustav Spörer was able to observe a certain number of anomalies and in particular the extraordinary from 1672 to 1713 recognized by Cassini, a period of half a century, during which spots appeared only in the southern hemisphere and still few in number.

 

  • Similarly in 1966, Mr. Raymond Richard, titular astronomer of the Paris-Meudon Observatory, relates that “the first signs of a new cyclic activity of sunspots appear at high latitudes, between 30 ° and 45 °, and more. high elsewhere the more the cycle is active; then the activity zones gradually move towards the equator, being around ± 15 ° at maximum activity, and falling to ± 5 ° for the last signs of cyclical activity ”.
     
  • In addition, the Sun would be the subject of cycles of a varied and intimately linked nature, not to mention that differential rotation would be an important key to understanding its phenomena. So we're talking about the 11-year cycle of sunspots, the 22-year cycle of solar magnetic field inversion, etc. Here are some words about it :
    • Thus Mr. Arnab Rai Choudhuri, author of “Nature's Third Cycle: A story of sunspots”, tells us that George Ellery Hale discovered in 1908 that sunspots are regions with strong magnetic fields and, in 1955, at the age 28, Eugene Newman Parker solved the fundamental equation in this area known as the dynamo equation and, by solving it, he discovered that he could explain many aspects of the sun's magnetic field, including understood the 11-year sunspot cycle that had seemed so completely mystifying to everyone until then.
    • In Mrs. Agnès Acker's book entitled “Astronomie Astrophysique”, it is mentioned that the intensity of the minima of the sunspots seems to evolve with a period of approximately 100 years (1810-1910-2010) and that a super- periodicity of around 400 years is suspected but cannot be confirmed with a sufficient number of observations.

At this point in my questioning, I still have to clarify and further document the following question :

  • What has research been able to determine at the level of the solar surface (photosphere) on the distribution, nature and properties of the different zones with sufficiently distinct rotational speeds?

For the continuation of things I started to integrate my photographic observations by superimposing a solar grid diagram on it using the Tilting Sun software. I also plan to use the Helio Viewer app for analysis. Attached is an example of my personal observation record for February 1, 2021, recorded with Tilting Sun and Photoshop5.

 

Have a nice day,

 

Max

 

Sources

  • Wikipedia

  • M. Raymond Michard, «Le Soleil», Que Sais-je, # 230, Presses universitaires de France, 1966.

  • M. Arnab Rai Choudhuri, «Natures’s Third Cycle: A story of sunspots» Oxford University press, 2015, édition Kindle.

  • Mme Agnès Acker, « Astronomie Astrophysique », 5e édition, Dunod, 2013.

BRAF
Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 03/09/2021 - 19:26
Central solar zone

The central solar zone is defined in SunEntry help as follows:

QUOTE

  • (Notes on the central zone (cg and cs) counts from the SIDC website) The central zone is defined as the circular area on the solar disk, with the same center as the solar disk, but with a radius that is half the solar radius. The "center of weight" position of the group determines if it is in the central zone. All spots belonging to a central zone group are counted, even if part of the group extends outside the limit circle. Conversely, none of the spots belonging to groups outside the central zone must be counted, even if some of them just fall within the limit. The central count for groups, spots and Wolf must always be less or equal to the corresponding total count. There is no relation between hemispheric counts and the central zone counts. The counting of the sunspots and the sunspot groups in the central zone is independent from the counting in the Northern and Southern hemisphere: a group or a sunspot appearing slightly North of the disk center will be counted once for the central zone and once for the Northern hemisphere. If sunspots or sunspot groups are close to the edge of the central zone, i.e. if they are at approximately half a solar radius away from the disk center, it can be difficult to determine if they are in or out of the central zone. In this case, the position of the sunspots or sunspot groups must be evaluated at 1200UT.

UNQUOTE

I never considered this zone for counting but may be other observers do.

Raf

maxsurlaroute
Affiliation
American Association of Variable Star Observers (AAVSO)
Thu, 03/11/2021 - 22:44
Central solar zone cg.cs in SunEntry

Hi Raf,

Thank you very much for those details.

I must admit that this escaped me during my first uses of SunEntry because I had limited myself to carefully reading the "SunEntry Help", the "The AAVSO Solar Observating Guide" and other documents concerning solar spots and groups.

I understand better this procedure (cg, cs).

For my part, I do not intend to consider this zone (cg, cs) because I already feed my own database by entering the latitude and longitude of each sunspot there for my purposes of studies and subsequent analyzes.

Have a nice day,

Max