[Robin Leadbeater]

I just used a Jeweller’s screwdriver but if the grub screw is tight then it seems unlikely that the collar has moved so it probably is not the reason for the micrometer becoming tight. With mine the locking collar is close to the spectrograph body when engaged and there is a definite gap with it disengaged. I will take a couple of photos.

Cheers
Robin

[Robin Leadbeater]

There is a knurled collar at the base of the micrometer held in position with a tiny cross head grub screw which is used to lock the micrometer at a given setting. Has that got tightened down? Mine is fully wound off (anticlockwise) and locked down with the grub screw.

Cheers
Robin

[Robin Leadbeater]

Meanwhile ZTF have “discovered” their second high proper motion star in the past 3 months
https://www.wis-tns.org/object/2023acmv
https://www.wis-tns.org/object/2024dum

Robin

[Robin Leadbeater]

Robin Leadbeater wrote:

That’s odd. According to time on the confirming spectrum on TNS, it was taken a day before the discovery date

Robin

Followed this up with the GOTO team. The date of the spectrum was indeed wrong and is now corrected in TNS

Robin

[Robin Leadbeater]

That’s odd. According to time on the confirming spectrum on TNS, it was taken a day before the discovery date

Robin

[Robin Leadbeater]

Stars with H alpha emission lines (of which there are several in the Pleiades) in a narrow band H alpha filter (where the solar spectrum has a deep absorption) might be interesting.

[Robin Leadbeater]

It is ok, it looks like they are now being diverted to spam

[Robin Leadbeater]

Hi Andy,

I don’t appear to have received any newsletters since no 72 last October. Are they archived anywhere ?

Cheers
Robin

[Robin Leadbeater]

Interesting. I don’t think the comparison between the mass deorbited and the amount of material in the Van Allen belt is particularly helpful as the two are not comparable (We already receive ~ 40T/day of metals from meteorites) but at the future projected rate of 23 satellite deorbits a day (in the paper) the amount of additional material would appear to be comparable.

[Robin Leadbeater]

I have just been listening to one of the scientists involved in that study on BBC world service Science in Action
https://www.bbc.co.uk/sounds/play/w3ct4sdl
starting at 22:40

Robin

[Robin Leadbeater]

Now classified spectroscopically as type IIn by Italian amateur Claudio Balcon

[Robin Leadbeater]

There could be some financial advantage to extending the time over which power can be generated rather than increasing capacity on the ground. For a region heavily dependent on solar power, the price of night time electricity must presumably attract a high premium due to the high cost of storage or alternative generating capacity.

[Robin Leadbeater]

I don’t see any convincing arguments for using LED lights with a high blue spectral content for outdoor lighting and many reasons why it should not be used. Why any council lighting engineers should still be pushing back on this these days when alternatives with a lower blue content are available is beyond me

Here is his Mario Motta’s review from a US perspective.
https://www.mariomottamd.com/street-lighting/

[Robin Leadbeater]

Robin Leadbeater wrote:

See a presentation on this at the 2018 joint BAA/AAVSO meeeting

https://britastro.org/event/baa-aavso-joint-meeting-on-variable-stars

Mario Motta – American Medical Association statement on street lighting

There could be a video of it somewhere on the website

[Robin Leadbeater]

Not sure why the quote was attributed to Melvyn, it was actually from Grant

Robin

[Robin Leadbeater]

Melvyn Joslin wrote:

I tried pointing out to the local lighting officer and my County Councillor that lower colour temperature LEDs were better, as they reduced scattered light in hazy/foggy conditions

You would probably have more success going on social media saying blue LED lighting causes cancer. (Unlike with 5G there is apparently some evidence to support this and has caused some towns in the US to rip out their recently installed blue LEDs in favour of lower temperature versions. See a presentation on this at the 2018 joint BAA/AAVSO meeeting). Failing this, pointing out the effect on wildlife might gain more traction among the general public, particularly if yo have any green councillors

[Robin Leadbeater]

Andy Wilson wrote:

Richard Berry is trying the Origin out for variable star photometry. There is the opportunity to use the green channel as with DSLRs, or all the light, depending on the goal of the observation.
The HOYS Citizen Science Project are accepting observations from ZWO Seestar 50mm telescopes, these use a colour CMOS chip. This is a research project run by Dirk Froebrich at the University of Kent, to monitor young stars.
Both of these approaches use the raw files saved by these smart-telescopes, rather than the processed images displayed on smartphones and tablets.
Andy

These ideas might attract people into scientific applications of their kit but these solutions are pretty suboptimal. It reminds me of the days of converting webcams for deep sky imaging. The results were impressive given the limitations of the kit but far from what came after based on the huge interest in imaging it generated. Hopefully the smart scope manufacturers might see there is a market for mono sensors which can take filters. ZWO should be perfectly placed to do this for example as their SeeStar uses the same CMOS sensor in colour version as another of their cameras which uses the mono version (There are apparently already people using Star Analyser on the front of this scope and even hacking into it to mount it internally, though the colour sensor is a big drawback)

There are other examples of areas where there is a tension between what is good for (marketing to) imagers and not for science. For example fancy mulit-coatings which make the difference between 95 and 98% are a disaster for short wavelength measurements.

[Robin Leadbeater]

Perhaps with these smart telescopes a swap out for a mono sensor might be feasible ? I used to do this kind microsurgery on webcams back in the day but my eyes and hands are not up to that now and I expect the pins are much closely spaced. If it uses a separate off the shelf camera module it might be possible though if there is a mono version. (Plus a firmware hack to get at the raw image before debayering)

With the Unistellar, being an open tube you can get in to put filters (or even a diffraction grating) in front of the camera

[Robin Leadbeater]

BTW looking at the example solar spectrum in the video, the resolution is nowhere near 2nm (more like 5-10x that). Compare with my simple “SEPSA” (Slit-EyePiece-Star Analyser) setup for example
http://www.threehillsobservatory.co.uk/astro/spectroscopy_18.htm
or the slitless collimated Junk Box design
http://www.threehillsobservatory.co.uk/astro/spectroscopy_19.htm

These are just a bit of fun though. A slit/fibre fed spectrograph really needs a guider module so you can find, focus and place the star on the slit/fibre and keep it there

Cheers
Robin

[Robin Leadbeater]

Grant Privett wrote:

Figure 1 is interesting

That pretty much matches what Christophe saw with the Star Analyser. If you normalise the spectra in the red/green then Neptune shows a slight blue excess and both planets have similar depth Methane absorption bands

[Author]

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