Close Approach of 2015 RN35

[PMSchu]

CNEOS predicts that this NEO will make a close approach on 2022-Dec-15 08:12 ± < 00:01 UT at a distance of 0.00459AU. H=23.1 magnitude, V relative=5.91 km/sec, 'Rarity'=2 & Condition Code=0. This is a medium-sized object, 63 - 140 m.

Using MPC's orbital elements for the epoch 2022 December 13 00:00 UT, ST4v predicts that this NEO will reach a maximum brightness of 13.4 magnitude on December 16, 822k km distant traveling through Lepus at ~70"/min. Close approach occurs on December 15 0300 EST (to the nearest hour) when ST4v predicts that it's 13.7 magnitude moving through Fornax at 104"/min, but below the horizon from Columbus, Ohio.

Here's an Interactive Atlas chart showing the predicted path of this NEO from 2022 December 14-24 for Columbus, Ohio: [attachment=2597]

Since this object will pass very close to earth, parallax will affect the predicted positions of this NEO as it passes. Anyone interested in observing it should download the MPC's NEAs at Today's Epoch datafile using SkyTools' MP download options & create charts for their location.

Good hunting,

Phil S.

[bigmasterdrago]

I made a stab at this large rock last night just after moonrise under pristine skies (Bortle 4). Its estimated magnitude was 13.4 with sky motion just over 1'/min. While it was ~40° high, it was in my most light polluted direction (south). The 13 incher at 250x was able to pull out single mag 13.0-13.2 stars seemingly easily, I was unable to fix the rock's location visually. I know it was there but it was just out of reach as both SkyTools and Horizons agreed on its position to within <" - 16 December 00:00CST RA 05 41 34.07 DEC -16 58 59.4. I need to configure ST to adjust the difficulty for stellar objects in my southern sky due to it claiming apparent to easy. I know better and should have expected these results.

I'll have another chance at a 13.4 mag big rock (~200 meter 2010 XC15) which will be much better placed for viewing in the early morning hours of December 27th. It will be moving >2'/min east thru Bootes high in the eastern sky (60+° near the beginning of astronomical twilight). Since this will be a 2LD pass, make sure to plot it for your location using the nearest element set.

[PMSchu]

One of the things that I learned recently is that if you download both MPC's MPCORB & NEAs at Today's Epoch data files, be sure to uncheck the NEO box when downloading MPCORB. If you leave the NEO box CHECKED when downloading MPCORB, all of the known NEOs will have their epochs updated to the MPC's current standard epoch of 2023 Feb 25 00:00 UT. If that happens to your NEOs, then they won't be updated to Today's Epoch until after 2023 Feb 25 because SkyTools stores & uses the future date. New discoveries will be added when they're discovered & will be updated with Today's Epoch, so they'll be fine.

Greg said that he's working on a fix for this condition. MPC has changed the way they handle the standard epoch & now use future epoch dates.

If you're downloading elements from HORIZONS for individual NEOs then you probably haven't encountered this issue.

Phil S.

[bigmasterdrago]

Correct. I saw your thread and very good advice. Thanks. I've not run across that issue yet. When I want to run an ephem for a close passer that may be in my realm of opportunity, I've learned, with SkyTools to always use the elements supplied by Horizon osculating at that specific date (near close pass). Otherwise it will not take into account the perturbations imposed by the Earth-Moon system.