100 days to go

Total solar eclipse of April 8, 2024.... 100 days to go.

Reworking Sol'Ex H-Alpha Images using IMPPG

I reworked my Sol'Ex images from Oct 1 & 14, 2023 using IMPPG 1.9.1 beta. CS4 was used to add false colours. 

140.000 Visitors

Since the start of my blog on December 2012, I'm counting an amazing number of 140.000 visits to my blog. Thanks for visiting my blog and hopefully I have managed to convey my passion for astronomy, solargraphy and related sciences.

Astronomical Highlights 2023

Again an interesting astronomical year "2023" with some amazing "wow" moments and again great learnings. I had to limit the list but these are my astronomical highlights:

#1 Comet C/2022 E3(ZTF) with 3 tails
#2 Saturn at opposition
#3 Sol'Ex images of the Sun in H-alpha and CaK
#4 Jupiter
#5 Circumscribed halo and parhelic circle

Worth mentioning:

#6 Sun in HeI (D3) spectrum
#7 Moon halo, Moondogs and paraselene circle
#8 Supernova SN2023ixf in M101
#9 M81
#10 Visit Radio Astronomy Center Humain
#11 Venus, Mercury and Pleiades

Lacerta Herschel Wedge - Brewster Angle

TLAPO80/480 with Lacerta Herschel Wedge and ASI290MM

Some information about my new Lacerta Herschel Wedge. According reviews a Herschel wedge or Herschel Prism would provide more details then the use of Solar film.

My objective is to get more details of the photosphere and the more specific on the granulation itself. Another objective is to use the wedge with my Sol'Ex. 

The Herschel Wedge is equipped with a neutral density filter ND3. On the back of the wedge it's noted that the total light reduction with ND3 filter us ND4.07.

This means that the wedge itself has a light reduction of  4.07 - 3 = ND1.07 . For both visual and photografic observation a value of ND1.07 is too low and even dangerous. To compare with my Solar film ND3.8 I would need to install a filter ND2.7 or  ND2.8. on the wedge. But for now I will keep using the ND3filter.

A value of ND1.07 means a transmission of :  T= 10 exp (-ND) = 10 exp (-1.07) = 0.0851 or 8.51%.

Another interesting one is Brewster Angle.The Brewster angle, named after the Scottish physicist Sir David Brewster, is the angle at which the reflected light rays from a non-metallic surface are fully polarized. In other words, the light waves that strike a surface at the Brewster angle are reflected in only one specific direction (polarized light), while the perpendicular light waves are absorbed.

The Brewster angle can be calculated with the following formula:

tan⁡(θB​)=n2/​n1​​

where θB​ is the Brewster angle,

n1​ is the refractive index of the medium from which the light comes (e.g., air),

n2​ is the refractive index of the medium in which the light is reflected (e.g., glass or water).

At the Brewster angle, the resulting reflection of light for a particular polarization direction is minimal, which can be useful in various optical applications such as my use of the Sol'Ex.

Air typically has a refractive index of approximately 1 (as an approximation), while the refractive index of glass (like in the Lacerta Herschel wedge) is typically between 1.4 and 1.6, depending on the type of glass.

Let's assume a refractive index of 1 for air and a refractive index of 1.5 for glass for simplicity. So, in this example, the Brewster angle for air and glass is approximately 56.31. According the website the Brewster Angle is 56.6°.

Above picture is taken with TLAPO80/480 f/6, ASI290MM and Herschel Wedge. Editing using new beta release of IMPPG and CS4 after stacking with AstroSurface Urania V1.

My Blog Statistics - Blogposts and Visits

A visual presentation of my @blogposts and #visits of my Astro Page blog. This year, blogpost number 2000 was posted. 

First light with Lacerta Herschel Wedge

The sky cleared unplanned so I could set up my mount with my new Lacerta Herschel Wedge.
With the set up I was not able to capture the entire solar disk. I tried to use my reducer but this was not succesful.

I'm not sure but the exposure time was almost at it's minimum. Need to follup this next time and for sure when the Sun climbes higher in the sky.

Setting:

TLAPO80/480 with ASI290MM

Herschel Wedge with ND3 filter

Exposure time 0.059ms, binning 1x1, 16bit, gain 0

Software: SharpCap 4.1, AstroSurface V1 Urania, IMPPG, CS4