Comparison between First Solar Picture by Fizeau and Foucault and mine 179 years later

F. Arago, Popular Astronomy, Volume 2, Book XIV, Chapter XXVII, p176 (1855)

The first successful photograph of the Sun was taken by the French physicists Louis Fizeau and Léon Foucault on April 2, 1845.For this, the solar light was reflected horizontally by a heliostat to a lens, at the focus of which a daguerreotype was placed. But the Sun is so bright that the exposure time was to be between 1/60 and 1/100 of a second: it was not possible to use the usual method of a cover removed and replaced manually on the lens. Fizeau and Foucault imagined an “original enough” shutter consisting of a plate with a horizontal slit of appropriate width, which they dropped in front of the camera: this was the ancestor of the curtain shutter. The picture showed sunspots aswell as limb darkening. The limb darkening was subject of debate those days. 

Compare with my recent picture of the Sun, 179 years later :)

References: 

- F. Arago, Popular Astronomy, Volume 2, Book XIV, Chapter XXVII, p176 (1855)

- NASA : Technology through time Issue sheet #40, First Sun Photo

Imaging Sun in Helium (D3) line

My Helios collegue, Walter, informed me about a new imaging software SHG_Main for spectroheliographic images of the Sun. My files from October 14, 2023, which included Sodium D1, D2 and Helium (D3) could not be processed using INTI software. So after installing SHG_Main I succesfully processed the data and after editing I got a solardisk in Helium D3. My first one even!

The software has a "spectrum" tab which searches for different lines. In my case I anchored Na (D1) and Na (D2) and after calculation of the dispersion factor the software found the He D3 line (see graph).

An Helium D3 image was made using the data from the spectrum tab and another image was made with -10 pixels further away from He D3 line. Both pictures were substracted from each other using CS4 and false colours were added. 

I do remember that the data set was made under windy conditions which prevented a smooth recording that day. 

Comparison between solar pictures in H-Alpha, CaK and He D3. All pictures taken on October 14,2023. All three pictures show prominences. 

Moon halo, Moondogs and paraselene circle

This evening the moon was surrounded by a 22° Halo, Moondogs east and west of the moon and paraselene circle (not parahelic circle as this is for the Sun).

Setting : Nikon D7500 15mm f/4 ISO1600 2,5s

Setting : Nikon D7500 10mm f/3.8 ISO1250 4s

Editing : CS4

Sun CaK What to see

 

What to see when we image the Sun in Ca K line?

- Plages or Chromospheric Faculae : Most of us are familiar with photospheric faculae which can normally only be observed towards the edge of the solar disc in white light when it is possible to view a higher region in the photosphere. These bright mottles can be up to 50,000km long and are caused by underlying magnetic fields. They are often a good predictor of future active region development and can also remain long after an active region has dissipated. The average lifetime of faculae is about 90 days and they are around several hundred degrees Kelvin hotter than the surroundings (therefore appear bright).Chromospheric faculae can be observed anywhere on the solar disc and they are an extension of the photospheric faculae into the chromosphere, details of this link are still not fully understood. Areas of very dense magnetically bright faculae or plage occur in active regions and are a good predictor of the occurrence of future sunspot formation (Evre, S. 1999). Polar faculae are short lived and only observed just before and around the solar minimum.

- Supergranulation Cells- Chromospheric Network Structure: in the quiet sun most of the chromosphere seen in Ca II K appears like a bright network pattern of irregularly shaped circles. The size of these cells is around 30,000-35,000 km in size and their average lifespan is around 20 hours. (Bhatnager, A. 2005). This is a pattern of weaker magnetic fields (the quiet network) where the magnetic elements are mixed in polarity. These are also called the intranetwork fields and the brighter edges can also be called faculae. The supergranulation cells are large scale convective horizontal flow, where material flows outwards from the centre and downward flow has been observed at the boundaries. The flow carries both polarities to the boundaries (Zirin H. 1988 p126).

- Bright rings around sunspots

- Sunspots

- K-Grains or bright points: K grains are 'intranetwork bright points' found in the quiet sun. Intranetwork bright points, cell flashes or cell grains, originate exclusively within cell interiors in quiet areas of the solar surface. These are observed almost exclusively in the Calcium H (396.85nm) and K lines (Rutten et al. 1991). They are intermittent localised brightenings which last less than a minute and often re-appear a few times at 2-4 min intervals at about the same place, and frequently occur in pairs. In Figure 2, the labelled brightenings are an example only. These bright points are tiny and good resolution is needed to observe these features. To identify them definitively, a time lapse study would need to be embarked upon and the brightenings studied to assess whether they follow the pattern of re-emergence and disappearance, again another good area for amateur study. It has been observed that these K grains do seem to correspond with G-band brightpoints observed in the intergranular lanes in the photosphere (Lite et al. 1998).

- Filaments

- Prominences

Source: https://solarnutcase.livejournal.com/1047.html

Succesvol VVS Weekend 7/8 oktober 2023 Blankenberge

Opnieuw een succesvol VVS weekend dat doorging op 7 & 8 oktober te Blankenberge. Helios was aanwezig met 7 leden, een record. 

Enkele hoogtepunten :

* Professor dr. Harold Linnartz sprak over ijs in de ruimte en in het laboratorium met het doel op zoek te gaan naar de bouwstenen van het leven. De vorming van moleculen gebeurt in de interactielaag tussen stof en ijs. Dit Solid State Astrochemistry proces beschrijft hoe moleculen worden gevormd. Er is een broos evenwicht tussen de vorming van het ijs en het afbreken van het ijs. Denk maar aan het permanent bombarderen en afbreken van het ijs door electronen, UV-, IR-licht of kosmische straling  en anderzijds de extreem koude omstandigheden die het ijs laten aangroeien

* Professor dr. Nick Van Remortel sprak over de Einstein-telescoop. Hij gaf meer technisch inzicht over het project dat ons moet toelaten zwaartekrachtsgolven te detecteren met een gevoeligheid die 10x hoger ligt dan de huidige LIGO of Virgo.

*Professor dr. Nienke van der Marel gaf toelichting bij het bouwen van planeten. Zij besprak resultaten van de ALMA telescoop over de afbeeldingen van schijven en de eerste tekenen van planeetvorming. Zij ontving recent de New Horizons in Physics Prize 2024 voor de voorspelling, ontdekking en modellering van ‘stofvallen’ in jonge circumstellaire schijven, waarmee een al lang bestaand probleem in planeetvorming is opgelost.

Ik wil ook nog de interessante lezingen vermelden van Thierry Van Driessche (komeet C/2023 A3), Wout Goesaert (op zoek naar actief supermassief zwarte gaten),  Merline Bruyndonckx (Fast Burst en hun astronomisch nut), Koen Geukens (Artemis en Space X) en Claude Doom over 50 jaar hemelkalender.

Helios delegatie in volle glorie ...

Scan time for Sol'Ex

The scanning of the solar disk using a Sol'Ex can be calculated using following formula

T = 8.79 * P / (f * v * Cos (delta))

• T = exposure time in s
• P = pixelsize in micron; include binning
• f = focal point of telescope in mm
• v = scanning time of telescoop, typical 4, 8, 16
• delta = declination of the sun

It looks like that the outcome of the exposure time compared with the scanning time is rather exponential.

Sun in Ca H, Ca K and H-Alpha

This morning a clear sky for solar observation. After focussing my Sol'Ex pictures were made of the Sun in Ca H, Ca K and H-Alpha.

Setting:

TSAPO60/360 with ASI290MM

Sol'Ex with Hoya 1.6 SSD 

Ca H , Ca K and H-alpha 

Speed : 8x, Capture Area, 1936x276, MONO16, binning 1x1, capturing with SSD

CaH and CaK Exposure : 10.23ms ,tilt -10

H-Alpha Exposure : 3.75ms, tilt -3.9
Software : SharpCap4, Inti, IMPPG and CS4