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It has been many many years since my last visual observations of meteors (back in 2010…). Last week I found the opportunity to observe a bit the peak of the Perseid shower.

I observed for a couple of hours, just before the moon rise, from my place in the relatively light polluted Heraklion of Crete. I was a bit tired since I have waken up in the morning and didn’t manage to get any sleep so definitely I missed some fainter ones. But there were a few bright Perseids that I saw with a couple of them being kind of spectacular!

Although the total number recorded was low (7 Perseids and 5 Sporadics) I enjoyed the observation. Sitting relaxed in a chair and viewing the nigh sky feels nice, especially when the anticipation on the next bright meteor is added.

You can find the particular observation log as Session ID 80974 at IMO.

I was disturbed to notice numerous horizontal lines in the video of my meteor camera (see the MetRec image). At the beginning I was afraid that this was due to the fact that the camera was powered in daylight (even with the possibility that the Sun passed through the fov!).

I asked around to find what was wrong. Fortunately, many people responded to my plea! Most refer to noise of power supply material, like bad connection with the socket, poor power supply, loose wiring, or even grounding issues.

On the contrary Tassos K. told me that this is probable due to the loose connection of the video cable than by any electric device. Indeed when the video cable connection at the pc was checked these lines disappeared.

So, I hope that this was the problem, although I will keep an eye to the power issues also!

UPDATED on 20/Nov/2013
After all it was indeed a grounding issue! The last time I opened the case for the camera I put the ground of the power supply for the case onto the thermal base where the camera is placed (see the green cable higklighted in the red region). After re-placing this cable the camera works without any more lines!

Zuluaga J.I., Ferrína, I, and Geens, S., 2013, arXiv:1303.1796
The orbit of the Chelyabinsk event impactor as reconstructed from amateur and public footage

The Chelyabinsk meteor is the most important impact event after the Tunguska event, almost 100 years before. The object that entered Earth on February 15, 2013, was a small-sized Apollo asteroid (with a diameter of 17-20m), and caused serious damages. This fact proves according to the authors that the number of Potential Hazardous Asteroids (PHA) are almost double that what is thought, although most of them (with diameters smaller than 100m) are not capable of global damage but can cause severe local damages. They state also the fact that the approaching direction was from the Sun side, which is a totally blind spot currently at the existing optical surveys.

During one observing night in December 2011, I noticed a strange “illumination” in the field, as the image from MetRec shows.

What is obvious from the above image is that there is too much light coming from the bottom, which affects the regions of interest, the flat-field image and the sensitivity image. As a consequence this area of the field-of-view is inactive.

Visual inspection of the lens didn’t reveal any dust. Unplugging the camera (Watec 902H2 Ultimate) and restarting MetRec a couple of times didn’t work either. It is possible, since I don’t remember well, that the camera started early enough and as it was looking to the west a lot of light was, possibly, captured by the camera and “insisted” through time, like a memory effect.

When the system started next night the “illumination” effect has left! What has happened? Nothing more than that the camera was off for many hours and the cover of the lens was on. Perhaps the last step was the critical one. Since then the system runs smoothly and I don’t intend to experiment further (but possibly may face it again…).

A short list of links for MetRec (meteor detection program):

• MetRec
• IMO’s Video Meteor Network
• IMO’s Video wiki
• Practical hints
• Common errors

Project

The Perseids 2010 have served as a great opportunity to experiment with video recording of meteors.

A DMK camera (DMK 21AF04.AS, The Imaging Source) equipped with a CCTV 2.8mm lens and UFO Capture v2.22 were used.

First Results:

In total, the camera worked for 17 nights recording 32 meteors (mainly Perseids).

Initially the exposure time of each frame was set (through the IC Capture program, provided with DMK cameras) at 1/30 s but only the brightest stars down to 1mag were visible making the orientation of the camera and the identification of the field a very demanding task. In order to make this task easier, without losing the video functionality, the final exposure time was selected to 1/5 s and stars up to 2-2.5 could be identified in the field.

Examples (meteors identified visually as Perseids) :

Meteor’s path and velocity estimation:

Above an image of another, visually identified, Perseid and below its equivalent “map”.

The “map” is an image of the changes in the field-of-view (fov). The blue points are constant light sources (mostly stars, but also other sources like artificial lights, light pollution, etc), which are “mapped” and create a mask. This mask is, subsequently, subtracted from each frame in order to highlight only the real changes in the fov shown as red points. A meteor can be identified as a linear series of red points.

So, in this case the meteor’s path is obvious as a red “line” with breaks due to the exposure time of each frame. From the known angular distance of beta and gamma Cygni, equivalent to 16.24 degrees, the scale of the image is determined to 0.1 degrees/pixel. So, the meteor’s path is estimated to 214±4 pixels which equals to 21.4±0.4 degrees. In order to determine the velocity only the central path of the meteor is estimated (68±4 pixels, which equals to 6.8±0.4 degrees), as only this part is in between 3 consecutive frames and its time duration equals to the exposure duration (1/5 s). Thus, the minimum velocity is estimated at 34±2 degrees/s (as seen on the sky).

Outcome:

Although the sensitivity is not great, as this system’s limiting magnitude is 2 – 2.5 mag, the recording of bright meteors may be of some use (especially for fireballs), so the system could provide valuable results. But further use was never achieved as the camera was returned to the owner (under loan from J.-M. Strikis).

System Configuration:

The DMK camera was a firewire camera so a PCI firewire card was used to connect the camera to the pc.

1. install the camera’s driver for the pc (link)

2. install IC Capture (link of trial version) – necessary to adjust camera’s parameters

After these the camera should work.

3. focus camera

4. setting UFO Capture v2 (link – trial mode of 30 days with full functionality) – [Apostolos Christou, Grigoris Maravelias, Vagelis Tsamis, “Meteors and how to observe them”, Workshop notes (in Greek), 5th Panhellenic Meeting Amateur Astronomers, Mt. Parnonas, Greece, 2010]

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Quickstarting UFOCapture v2:

1. Double-click “UFO” icon. You now see four tabs: “Input”, “Operation”, “Profile”,

2. “DB”

Check that Detect Size= 2 (above the viewer, when you hit the “Live” Tab on the right).

Then go through the four tabs on the left as follows:

On “Input”:

– Select appropriate “Video” stream, eg “Hi-Speed USB DVD”

– Check that the settings are as follows

Size=640×480, Codec=AVI,fps=25

Head=35, Tail=35, Diff=1

Min(frm)=3, Max(sec)=8, EXsize=50

Detect Level Noise Tracking: Tick.

DLratio= 115, MinDL=5, MinL-N=2

Scintillation Mask: Tick.

SMLevel=107, SMSpeed=2, SMSize=3

Superimpose: on: tick, m: tick, UTC: ticked.

On “Operation”:

Snapshot, Map bmp: tick. Detect Schedule (1 of 2; tick or untick as appropriate): eg 17:30 – 07:00

Minimum Free Space: eg 1000MB. Stop: tick. Beep at Capture Start (tick or untick as appropriate).

On “Profile”

Camera ID= MO

Camera Name= WATEC902DM2S

Lens Name= COMPUTAR8MM

Interlace: tick

On “DB”

DB dir = /xxx/yyy (do >not< type it in; rather, click on button to the right and select it from the list; need to create directory *before* linking to it).

pm/am per day: tick.

Finally, press “Live” and then “Detect”.

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You may need to play around with the parameters in order to obtain consistent records. In the DMK case what was needed [thanks to Apostolos Christou] was to change only the scintillation mask level, from 107 for Watec to 130 for DMK.

The Geminids are one of the best meteor showers of the year with numerous (ZHR~120) and bright (r~2) meteors! The parent body is an asteroid named 3200 Phaethon, which is believed to be a candidate for an extinct cometary nucleus, a mystery by itself. Moreover, during the last perihelion passage of the asteroid its magnitude increased unexpectedly (almost doubled), which is thought to be connected to some ejected dust originated from break-down of surface rocks. But this dust can account only for the 0.01% of the total material which is needed to supply the stream in order to see this activity each year this show.

How this object has manage to give out so much material? Geminids are not ready yet to reveal their mysteries…

The source and paper ( by journal or author) / Jewitt D. & Li J., Activity in Geminid parent (3200) Phaethon, AJ, 140, 1519, 2010.