New aperture photometry technique for fast moving fly-by NEOs: detection of the 2.58s rotation period of 2024 BX1.

• DOI: 10.5194/epsc2024-719
• Publication Date: 2024-07-03T11:09:04Z
• Authors: Maxime Devogele; Luca Buzi; Marco Micheli; Juan Luis Cano; Emmanuel Jehin; Marin Ferrais; Francisco Ocaña; Dora Föhring; Charlie Drury; Zouhair Benkhaldoun; Peter Jenniskens
• Keywords: Rotation period

Circular aperture photometry, is a crucial method utilized in astronomical observations for measuring the flux emitted by point sources [1]. Its utility spans diverse phenomena, encompassing tasks such as determining absolute magnitude and spin period of asteroids [2]. In conducting traditional circular photometry on objects motion, it's essential to adjust exposure time prevent both moving object stars from appearing elongated image. When dealing with near-Earth (NEOs) challenging due their rapid motion sky (from several arc-seconds per minute arc-degree minutes during close fly-bys). Such angular necessitates brief times, resulting significant portion observation being consumed CCD read-out rather than actual on-sky observations. This limitation has hindered detection extremely rotation periods. The quickest period, P = 2.99 s, was identified using camera [3].Hence, when limited slow time, most straightforward dependable acquiring high-quality data these fast conduct sidereal tracking observations, enabling asteroid appear trail images.We are presenting here novel obtain photometric measurements trailed asteroids. Our strategy capitalizes across while keeping sharp. enables us employ standard apertures stars, facilitating astrometric field calibration. As asteroids, they spanning hundreds pixels image we need new approach extract variation. For square or rectangular oriented parallel direction NEO's trail. optimizes signal-to-noise ratio extracted within Subsequently, traverse along gather over time.We applied our technique three recently observed targets at Schiaparelli observatoty TRAPPIST-North telescope [4]. first two targets, 2023 CX1, 2024 BX1, impacted Earth shortly after EF perfomed very fly-by.For minimal variation noted, suggesting either spherical shape span. A double-peaked phase curve obtained 18.33 seconds. contrast, analysis BX1  revealed it be fastest rotating date, measured 2.5888 +- 0.0002 0.7 amplitude suggest an shape. For EF, detected around 3.95 through tracked However, demonstrate that single 90-second aligns accurately regular phased. [1] Howell, S. B. 1989, Publications Astronomical Society Pacific, 101, 616[2] Mommert, M. 2017, Astronomy Computing, 18, 47[3] Beniyama, J., Sako, S., Ohsawa, R., et al. 2022, Japan, 74, 877[4] Jehin, E., Gillon, M., Queloz, D., 2011, Messenger, 145, 2TRAPPIST-North project funded University Liège, collaboration Cadi Ayyad Marrakech (Morocco) Belgian Fund Scientific Re- search (FNRS) under grant PDR T.0120.21. E. Jehin FNRS Senior Research Associate