SonotaCo.JP

[Skymagic]

Hello SonotaCo and all,

With your permission, I would like to ask a few questions regarding UFO Orbit 3.04. I'll start with some inaccuracies in the U.csv file that I noticed. This is what the header of this table looks like now:

_Version,_#,_localtime,_mjd,_sol,_ID1,_ID2,_amag,_ra_o,_de_o,_ra_t,_de_t,_
elng,_elat,_vo,_vi,_vg,_vh,_a,_q,_e,_p,_peri,_node,_incl,_shower,_dr,_dv%,_dd,_mag,_Qo,_delay,_dur,_av,_Voa,_Pra,_Pde,_GPlng,_GPlat,_ra1,_de1,_az1,_
ev1,_lng1,_lat1,_H1,_LD1,_Qr1,_Qd1,_ra2,_de2,_lng2,_lat2,_H2,_LD2,_Qr2,_Qd2,_LD21,_az1r,_ev1r,_evro,_evrt,_Nts,_Nos,_leap,_rstar,_
ddeg,_cdeg,_drop,_inout,_tme,_dt,_GD,_Qc,_dGP,_Gm%,_dv12%,_zmv,_Ed,_Ex,_QA,_Y_ut,_M_ut,_D_ut,_h_ut,_m_ut,_s_ut,_No,_Qp,_pole_sd,_
rao_sd,_dco_sd,_vo_sd,_rat_sd,_det_sd,_vg_sd,_a_sd,_1/a,_1/a_sd,_q_sd,_e_sd,_peri_sd,_node_sd,_incl_sd,_Er_sd,_ZF,_OH,_ZHR,_
dummy4,_dummy3,_dummy2,_dummy1,_SC_N,_Org_N,_Org_Er,_CMJD

Please note that it is missing the 'az2' and 'ev2' fields and this appears to be a software bug. I sometimes use these values in my work, and I have to additionally obtain them using UFO Analyzer, which is not very convenient. If you could find the time to correct this error, I would be very grateful. I hope you will not consider my request immodest.

In addition, the table has several new fields that were not in the previous manual. I also could not find information on the forum, so I have to contact you directly. Please tell me what the following fields mean: OH, ZF, Er_sd, Voa and ZHR.

The abbreviation ZHR is commonly used to refer to the zenith hour rate but I don't see how it can be used for a single meteor since the number of meteors recorded per unit of time is usually used to define ZHR. Please help me understand this.

I'm afraid I also don't fully understand the meaning of the Pra/Pde parameters. The manual provides a brief description and even an illustration, but in such a projection the directions of the vectors are not entirely obvious. I have attached to this message what I think is a better drawing. Do I understand correctly that Pra/Pde are the Ra/Dec coordinates of the points to which vectors n1 and n2 are directed?

I would also like to clarify the meaning of the LD1/LD2 parameters: are they measured along the line of sight, looking directly at the meteor from the observation point, or is it the distance from the observation point to the projection of the meteor’s start/end points along the Earth’s surface?

I realize I may have asked a lot of questions, and I really hope I haven't burdened you too much. Thank you very much in advance!

[SonotaCo]

[Skymagic]

Dear SonotaCo,
Thank you very much for your prompt and informative response!

[SonotaCo]

[Skymagic]

Dear SonotaCo,
Once again thank you for your quick and helpful response! I have already read the publications you suggested and have largely clarified the situation for myself. Now I have no reason to be mistaken.

[Skymagic]

Hello SonotaCo,
with your permission, I would like to ask another question.
Last time you mentioned that the ZHR parameter is not calculated with UFO Orbit because it is difficult to take visibility conditions into account.
Nevertheless, this parameter is a very important characteristic of meteor activity, which is needed quite often.
If possible, can you please tell me if you calculate ZHR in your works? If yes, how exactly?
I tried to search for this information on the forum, but alas without success. I would be very grateful if you could reply. Thank you very much in advance!

[SonotaCo]

[Skymagic]

Dear SonotaCo,
as before, I am very grateful for your quick reply and interesting thought. If I am not mistaken, in big astronomy the limiting magnitude of the stars present in the frame is used to determine the observing conditions. Since UFO Analyzer always knows which stars are in the frame, it probably makes sense to define seeing conditions as the ratio of the number of visible stars to the total number of stars in the catalog. In essence, this is very similar to your idea of estimating sporadic meteor backgrounds, but stars can be used as a tool. You could also try to measure the observed stellar magnitude of bright stars and compare it to the catalog: the decrease in brightness will depend on atmospheric transparency.

In addition, the comparison can be made not with the catalog, but with some reference video frame. Obviously, this approach will require additional calibration, but it can be done at the stage of creating a processing profile using a frame with known favorable observing conditions.

I would also like to offer you an article that I discovered just today. Apparently, the authors have achieved success with automatic ZHR determination (see pages 9-10). You may find it useful.