2026
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If a mass shrinks to half of its size then how many times does it’s rotational velocity increase by?
Short answer: it increases by a factor of 4. Here’s why (under the usual physics assumptions): So if the object shrinks to half it’s size: To keep constant: Angular momentum…
Pulsar Timings
It is often stated that pulsar timings are very stable and hence used as a cosmic clock by astronomers. Yet, on a live demonstration at Dwingaloo Observatory in Netherlands tonight,…
What are the Tsys, AEFF, and SEFD of 25m Dwingaloo dish?
There is no single officially published, modern value for the system temperature (Tsys) or SEFD of the 25 m Dwingeloo radio telescope that’s easy to point to. What follows is…
LRO-H1 Radio Telescope (86cm x 86cm Ptarmigan Triffid 4x4 Dipole Array)
Radio observation in hydrogen line (1420MHz)
Screenshot LRO-H1 data collection ezCol-py with RTL-SDR v3–23/1/2025@1240
How to use GLon.py in ezRA (Easy Radio Astronomy)
ezRA’s ezGLon.py program studies cross sections of the Milky Way, along one Galactic Longitude (GLon). ezRA’s ezGLon.py program processes *GLon.npz files. Above, the ezGLon.py program errored because it found *Gal.npz…
Easy Radio Astronomy Software (ezRA)
LRO-H2 Radio Telescope (150cm Solar Cooker Dish)
Radio observation in hydrogen line (1420MHz)
Hydrogen Line peak (H-Line, 1420 MHz) screen capture from ezCol.py capture software (part of ezRA suite) collecting data from a RTL-SDR Blog v3 Software Defined Radio on LRO-H2 radio telescope (150cm dish) on 22/1/2026
What is the impedance of 1420 Mhz (1.42 GHz) [atomic neutral hydrogen line] dipole?
A half-wave dipole resonant at 1420 MHz (the hydrogen line) has essentially the same impedance as at any other frequency: In practice The actual feedpoint impedance will vary depending on…
When I observe Milky Way in hydrogen, the centre of the galaxy has little hydrogen line emission. Why is that?
What you’re seeing is real, and it surprises a lot of people the first time they map the Galaxy in the 21-cm line. In short: the Galactic centre is not…
When I detect hydrogen with my radio telescope, is it coming from the optically bright spiral arms or the optically dark areas between them?
Mostly from the optically dark regions between the spiral arms, not from the bright arms themselves. Here’s why that happens, and how it matches what you’re detecting. 1. What the…