My Rambling Thoughts

The lastest Pi

One year after Stretch was released, I finally upgraded to it from Jessie. I put it off because the recommended way was to install it on a new SD card.

There is an official guide to upgrade in-place, but it is discouraged. It is really simple:

In /etc/apt/sources.list and /etc/apt/sources.list.d/raspi.list, rename jessie to stretch.

Then, run these:

sudo apt-get update
sudo apt-get -y dist-upgrade

(This is apparently the Debian way.)

It took over a day to download all the packages... the server is really slow.

The reason this approach is discouraged is that if things go wrong, you need to be reasonably comfortable issuing "arcane" Linux commands to make it work again. Luckily for me, I did not make much changes and all it did was ask me to choose between my modified config files or the new ones. I always choose the new one and re-apply my modifications after the installation, unless my changes are the only changes.

I have upgraded my Ubuntu in-place from 10.04 to 12.04 to 14.04 to 16.04, mostly problem-free. 18.04.01 is almost available, but I'll wait another three months. :-P

One thing I've wanted to do is to change to 64-bit version — 32-bit OS is passe these days. Almost everyone says a reinstallation is needed, that's why I've been putting it off. But I just read a post from someone who had done it — successfully. Doable, but scary. I need to think about it. :lol:

In-place upgrade is "fun", but the easiest and cleanest is to install 64-bit 18.04.01. I don't have that many customizations anyway.

An era passes

2008 to 2018. Ten years. End of an era.

An expensive month

25/6Car servicing$1,061.44
6/7Air-con servicing$408.74
14/7The Lion King musical *$398.00
16/7Air-con check-up$85.60
23/7Change air-con compressor$845.30
26/7Bike COE$7,073.00
26/7MakeToys MTRM-09 Downbeat (Jazz) 2~S$108.00

* Although it was paid for last year.

2 Excluding overseas shipping around S$6.70.

The air-con broke down six days after servicing. What luck. The Daikin personnel took 5 minutes to diagnose the compressor was spoilt — it was the easiest $86 to earn. The cheapest and least disruptive option is to change the compressor. Let's see how long it lasts.

The bike PQP went as low as $5,005 in Nov 2017. I paid $2k more for 8 more months. Bike PQP is on a downward trend. August PQP is $6,819, but I could not opt for it as my COE expires on 31th July.

When I renewed, the website reminded me that I could get $3.5k if I scrapped the bike instead. If I renewed, I could only get S$2k if I scrap before Apr 2023.

Anyway, my bike cannot be used after June 2028 (so I lose one month). LTA wants to reduce the bike quota, yet is desperate to keep COE low and force old bikes off the road. Let's see if the ruling will change.

A rare clear night

Field report, posted on CN:

Last night (23 June) was the first cloud-free night I had in almost a month.

I had taken excellent seeing for granted in past months. But it was very bad in June. I managed to observe only on three nights, and even then, there were very thin high-level clouds that reduced Jupiter's brightness.

Not yesterday. I observed around 8pm. Jupiter was at 59 degrees altitude. It shone very brightly and the GRS just rotated into view. Wonderful!

I have an array of cheap eyepieces, but I have settled on just three for Jupiter: 15mm (100x @ 1.2mm exit pupil), 10mm (150x @ 0.79mm e.p.) and 8mm (187.5x @ 0.6mm e.p.). The last two are a perfect match for my 127SLT.

It did not disappoint. With my 8mm EP, Jupiter was still bright — whitish with brown belts and a pale orange GRS — and showed as much details as my scope could give.

(In comparison, on a poor night, 10mm EP is already marginal.)

As I had a good feeling about the seeing, I brought along my 6mm EP (250x @ 0.48mm e.p.). With it, Jupiter was still pretty bright and detailed, and the main belts were still brownish! That's how I knew seeing was excellent!

(I could go higher if I had brought my 2x extender along. I had stopped doing so as there was no point. But it was nice to see how brightness limits magnification.)

So, I took out my binoviewer. My lowest EP pair was 15mm. (I had been too optimistic about viewing conditions.) In the past few times, even that was too much — it stole so much light that it was dimmer than 10mm solo, and looked worse than 8mm solo. (On those same nights.)

Yesterday was different. I had enough light at both 15mm and 10mm. I had a 8mm pair, but I didn't bring the second EP along. 10mm is about the highest I can use on my binoviewer anyway — it is as bright as 6mm solo. I was very optimistic.

Strangely, I had more issues with my 15mm than 10mm EP. While there is some pseudo-3D look, it looked a tad softer. I will continue my struggles with binoviewing another time. :lol:

A very satisfying night.


The Moon was just next to Jupiter, so I slewed over for a quick look after viewing Jupiter. It looked a bit tighter in the 15/70 EP than I remembered — perhaps it was closer this time.

When the Moon becomes full, I must pull out my ES 11/82 EP and see why I can't fit it in! :lol:

I forgot to use the binoviewer on the Moon! :duh:

A big view of Jupiter, or not

Last Friday (22 June), the skies cleared up, so I made a trip down to my local observatory (Science Centre) for their weekly stargazing session.

My objective is to view Jupiter through some bigger scopes and see how much I'm missing out.

The main telescope is a 16" f/13 Cassegrain reflector, housed in a 2nd-floor dome. I have very high expectation. If they target 1mm exit pupil, the magnification would be 400x! (The sky here can support such magnification on good nights — with room to spare.)

Unfortunately, the last time I was there, clouds had rolled in and all I could see was a dim brown marshmallow.

This time, they set up a C8 (8" f/10) at the open space as well, also pointing at Jupiter. Wonderful! It'll be a more meaningful comparison against my scope — at least I can afford to upgrade to this scope if it proved much better!

After half-an-hour of waiting (there is a time slot and you need to queue), it was finally my turn. I looked up. Sky was clear. Jupiter was shining bright at 55 degrees altitude. Perfect!

What fabulous sight awaited before me?

A bright white disc. It was big, but not as big as I had expected. I could vaguely see traces of the main belts. And three donuts on one of its side.

"Is it focused?", I asked.

Why sure it is, the person manning it answered. He even double checked.

Hmm. I went back to make the most of my time at the scope. (There is no set limit, but keep in mind the queue behind you.)

After that, I checked what eyepiece was used. It was a 40mm Tele Vue eyepiece. The magnification works out to be 130x (@ 3mm exit pupil).

Disappointed and puzzled, I exited the dome, climbed down the stairs and walked over to the C8. After a short wait, it was my turn. Jupiter was very bright and very small. And it was a little out-of-focus.

This time, the person manning the scope said I could adjust the focus. Finally, Jupiter snapped into focus. I could just barely make out the two main belts in brown. It was too bright.

I gave up after a while because the image was just too small and glaring to see any details beyond the main belts. The C8 was on a manual equatorial mount and needed constant adjustment. I looked at the eyepiece. It was a 40mm Tele Vue eyepiece. The magnification is just 51x (@ 4mm exit pupil).

"Jupiter is pretty small", I remarked. The person agreed. She said this scope was meant to view the Moon.

I gazed up at the sky. Jupiter was still shining bright and clouds were still some way off. If I hurried home, perhaps I could get a proper view of Jupiter.

What went wrong?

First, I wonder if the focal point of my eyes is so far from norm? Even with my glasses?

Second, it didn't dawned to me that I could ask to adjust the focus myself.

But lastly and most disappointingly, the magnifications used were too low. They should at least be doubled: 100x for C8 and 250x for the main scope.


When I reached home, clouds had blanketed the skies. Unexpectedly, they blew over rather quickly (within an hour), so I hurried out to observe.

I used both 15mm EP (100x @ 1.2mm exit pupil) and 10mm EP (150x @ 0.79mm e.p.). Jupiter was at 73 degrees altitude and was bright white, but not excessively so, much sharper and detailed. As a bonus, the GRS was in view. The four moons were dots with airy disc around them (as usual).

I did not go higher as high-level clouds were limiting Jupiter's brightness (but not its stability).

I had my answer.