The Palomar Transient Factory (PTF) is a multiepochal robotic survey of the northern sky that acquires data for the scientific study of transient and variable astrophysical phenomena. The camera and ...telescope provide for wide-field imaging in optical bands. In the five years of operation since first light on 2008 December 13, images taken with Mould-R and SDSS-g′ camera filters have been routinely acquired on a nightly basis (weather permitting), and two different Hα filters were installed in 2011 May (656 and 663 nm). The PTF image-processing and data-archival program at the Infrared Processing and Analysis Center (IPAC) is tailored to receive and reduce the data, and, from it, generate and preserve astrometrically and photometrically calibrated images, extracted source catalogs, and co-added reference images. Relational databases have been deployed to track these products in operations and the data archive. The fully automated system has benefited by lessons learned from past IPAC projects and comprises advantageous features that are potentially incorporable into other ground-based observatories. Both off-the-shelf and in-house software have been utilized for economy and rapid development. The PTF data archive is curated by the NASA/IPAC Infrared Science Archive (IRSA). A state-of-the-art custom Web interface has been deployed for downloading the raw images, processed images, and source catalogs from IRSA. Access to PTF data products is currently limited to an initial public data release (M81, M44, M42, SDSS Stripe 82, and the Kepler Survey Field). It is the intent of the PTF collaboration to release the full PTF data archive when sufficient funding becomes available.
Photometric calibration to image5% level is frequently needed at arbitrary celestial location. However, existing all-sky astronomical catalogs do not reach this accuracy, and time consuming ...photometric calibration procedures are required. I fitted the Hipparcos B sub(T) and V sub(T) magnitudes, along with the 2MASS J, H, and K magnitudes of Tycho-2-catalog stars with stellar spectral templates. From the best-fit spectral template derived for each star, I calculated its synthetic SDSS griz magnitudes and constructed an all-sky catalog of griz magnitudes of bright stars (V image 12). Testing this method on SDSS photometric-telescope observations, I find that the photometric accuracy, for a single star, is usually about 0.12, 0.12, 0.10, and 0.08 mag (1 capital sigma ), for the g, r, i, and z-bands, respectively. However, by using image10 such stars, the typical errors per calibrated field (systematic statistical) can be reduced to about 0.04, 0.03, 0.02, and 0.02 mag, in the g, r, i, and z-bands, respectively. Therefore, in cases for which several calibration stars can be observed in the field of view of an instrument, accurate photometric calibration is possible.
I present the results of Monte Carlo orbital simulations of Galactic Neutron Stars (NSs). The simulations take into account the up-to-date observed NS space and velocity distributions at birth, and ...account for their formation rate. I simulate two populations of NSs. NSs in the first population were born in the Galactic disk at a constant rate, in the past 12 Gyr. Those in the second population were formed simultaneously 12 Gyr ago in the Galactic bulge. I assume that the NSs born in the Galactic disk comprise 40% of the total NS population. Since the initial velocity distribution of NSs is not well known, I run two sets of simulations, each containing3 × 106
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simulated NSs. One set utilizes a bimodal initial velocity distribution and the other a unimodal initial velocity distribution, both are advocated based on pulsars observations. In light of recent observational results, I discuss the effect of dynamical heating by Galactic structure on NS space and velocity distributions and show it can be neglected. I present catalog of simulated NS space and velocity vectors in the current epoch, and catalog of positions, distances and proper motions of simulated NSs, relative to the Sun. Assuming there are109
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NSs in the Galaxy, I find that in the solar neighborhood the density of NSs is about2 - 4 × 10-4 pc-3
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, and their scale height is about 0.3–0.6 kpc (depending on the adopted initial velocity distribution). Moreover, I estimate that about 60–70% of the NSs born in the Milky Way are gravitationally unbound to the Galaxy. These catalogs can be used to test the hypothesis that some radio transients are related to these objects.
Palomar Gattini-IR is a new wide-field, near-infrared (NIR) robotic time domain survey operating at Palomar Observatory. Using a 30 cm telescope mounted with a H2RG detector, Gattini-IR achieves a ...field of view (FOV) of 25 sq. deg. with a pixel scale of 8 7 in J-band. Here, we describe the system design, survey operations, data processing system and on-sky performance of Palomar Gattini-IR. As a part of the nominal survey, Gattini-IR scans 7500 square degrees of the sky every night to a median 5 depth of 15.7 AB mag outside the Galactic plane. The survey covers 15,000 square degrees of the sky visible from Palomar with a median cadence of 2 days. A real-time data processing system produces stacked science images from dithered raw images taken on sky, together with point-spread function (PSF)-fit source catalogs and transient candidates identified from subtractions within a median delay of 4 hr from the time of observation. The calibrated data products achieve an astrometric accuracy (rms) of 0 7 with respect to Gaia DR2 for sources with signal-to-noise ratio > 10, and better than 0 35 for sources brighter than 12 Vega mag. The photometric accuracy (rms) achieved in the PSF-fit source catalogs is better than 3% for sources brighter than 12 Vega mag and fainter than the saturation magnitude of 8.5 Vega mag, as calibrated against the Two Micron All Sky Survey catalog. The detection efficiency of transient candidates injected into the images is better than 90% for sources brighter than the 5 limiting magnitude. The photometric recovery precision of injected sources is 3% for sources brighter than 13 mag, and the astrometric recovery rms is 0 9. Reference images generated by stacking several field visits achieve depths of 16.5 AB mag over 60% of the sky, while it is limited by confusion in the Galactic plane. With a FOV 40× larger than any other existing NIR imaging instrument, Gattini-IR is probing the reddest and dustiest transients in the local universe such as dust obscured supernovae in nearby galaxies, novae behind large columns of extinction within the galaxy, reddened microlensing events in the Galactic plane and variability from cool and dust obscured stars. We present results from transients and variables identified since the start of the commissioning period.
High-cadence transient surveys are able to capture supernovae closer to their first light than ever before. Applying analytical models to such early emission, we can constrain the progenitor stars' ...properties. In this paper, we present observations of SN 2018fif (ZTF 18abokyfk). The supernova was discovered close to first light and monitored by the Zwicky Transient Facility (ZTF) and the Neil Gehrels Swift Observatory. Early spectroscopic observations suggest that the progenitor of SN 2018fif was surrounded by relatively small amounts of circumstellar material compared to all previous cases. This particularity, coupled with the high-cadence multiple-band coverage, makes it a good candidate to investigate using shock-cooling models. We employ the SOPRANOS code, an implementation of the model by Sapir & Waxman and its extension to early times by Morag et al. Compared with previous implementations, SOPRANOS has the advantage of including a careful account of the limited temporal validity domain of the shock-cooling model as well as allowing usage of the entirety of the early UV data. We find that the progenitor of SN 2018fif was a large red supergiant with a radius of and an ejected mass of . Our model also gives information on the explosion epoch, the progenitor's inner structure, the shock velocity, and the extinction. The distribution of radii is double-peaked, with smaller radii corresponding to lower values of the extinction, earlier recombination times, and a better match to the early UV data. If these correlations persist in future objects, denser spectroscopic monitoring constraining the time of recombination, as well as accurate UV observations (e.g., with ULTRASAT), will help break the extinction/radius degeneracy and independently determine both.
The Palomar Transient Factory (PTF) is systematically charting the optical transient and variable sky. A primary science driver of PTF is building a complete inventory of transients in the local ...universe (distance less than 200 Mpc). Here, we report the discovery of PTF 10fqs, a transient in the luminosity 'gap' between novae and supernovae. Located on a spiral arm of Messier 99, PTF 10fqs has a peak luminosity of Mr = --12.3, red color (g -- r = 1.0), and is slowly evolving (decayed by 1 mag in 68 days). It has a spectrum dominated by intermediate-width H Delta *a (930 km s--1) and narrow calcium emission lines. The explosion signature (the light curve and spectra) is overall similar to that of M85 OT2006-1, SN 2008S, and NGC 300 OT. The origin of these events is shrouded in mystery and controversy (and in some cases, in dust). PTF 10fqs shows some evidence of a broad feature (around 8600 A) that may suggest very large velocities (10,000 km s--1) in this explosion. Ongoing surveys can be expected to find a few such events per year. Sensitive spectroscopy, infrared monitoring, and statistics (e.g., disk versus bulge) will eventually make it possible for astronomers to unravel the nature of these mysterious explosions.
We present here the analysis of about 19,500 new star hours of low ecliptic latitude observations (|b| < or =, slant 20degrees) obtained by the Hubble Space Telescope's Fine Guidance Sensors over a ...time span of more than nine years, which is in addition to the ~12,000 star hours previously analyzed by Schlichting et al. Our search for stellar occultations by small Kuiper Belt Objects (KBOs) yielded one new candidate event corresponding to a body with a 530 + or - 70 m radius at a distance of about 40 AU. (4) Regardless of the exact power law, our results suggest that small KBOs are numerous enough to satisfy the required supply rate for the Jupiter family comets. This suggests that small KBOs are undergoing collisional erosion and that the Kuiper Belt is a true analog to the dust producing debris disks observed around other stars.
We have identified a luminous star at the position of supernova (SN) 2011dh/PTF11eon, in pre-SN archival, multi-band images of the nearby, nearly face-on galaxy Messier 51 (M51) obtained by the ...Hubble Space Telescope with the Advanced Camera for Surveys. This identification has been confirmed, to the highest available astrometric precision, using a Keck-II adaptive-optics image. The available early-time spectra and photometry indicate that the SN is a stripped-envelope, core-collapse Type IIb, with a more compact progenitor (radius ~ 1011 cm) than was the case for the well-studied SN IIb 1993J. We infer that the extinction to SN 2011dh and its progenitor arises from a low Galactic foreground contribution, and that the SN environment is of roughly solar metallicity. The detected object has absolute magnitude M 0 V --7.7 and effective temperature ~6000 K. The star's radius, ~1013 cm, is more extended than what has been inferred for the SN progenitor. We speculate that the detected star is either an unrelated star very near the position of the actual progenitor, or, more likely, the progenitor's companion in a mass-transfer binary system. The position of the detected star in a Hertzsprung-Russell diagram is consistent with an initial mass of 17-19 M . The light of this star could easily conceal, even in the ultraviolet, the presence of a stripped, compact, very hot (~105 K), nitrogen-rich Wolf-Rayet star progenitor.
A relatively unexplored phase space of transients and stellar variability is that of second and sub-second timescales. We describe a new optical observatory operating in the Negev desert in Israel, ...with a 55 cm aperture, a field of view of 2.°6 נ2.°6 (≈7 deg2) equipped with a high frame rate, low read noise, CMOS camera. The system can observe at a frame rate of up to 90 HZ (full frame), while nominally observations are conducted at 10–25 Hz. The data, generated at a rate of over 6 Gbits s−1 at a frame rate of 25 Hz, are analyzed in real time. The observatory is fully robotic and capable of autonomously collecting data on a few thousand stars in each field each night. We present the system overview, performance metrics, science objectives, and some first results, e.g., the detection of a high rate of glints from geosynchronous satellites, reported in Nir et al. 2020.
Abstract We present a sample of 34 normal Type II supernovae (SNe II) detected with the Zwicky Transient Facility, with multiband UV light curves starting at t ≤ 4 days after explosion, and X-ray ...observations. We characterize the early UV-optical color, provide empirical host-extinction corrections, and show that the t > 2 day UV-optical colors and the blackbody evolution of the sample are consistent with shock cooling (SC) regardless of the presence of “flash ionization” features. We present a framework for fitting SC models that can reproduce the parameters of a set of multigroup simulations up to 20% in radius and velocity. Observations of 15 SNe II are well fit by models with breakout radii <10 14 cm. Eighteen SNe are typically more luminous, with observations at t ≥ 1 day that are better fit by a model with a large >10 14 cm breakout radius. However, these fits predict an early rise during the first day that is too slow. We suggest that these large-breakout events are explosions of stars with an inflated envelope or with confined circumstellar material (CSM). Using the X-ray data, we derive constraints on the extended (∼10 15 cm) CSM density independent of spectral modeling and find that most SN II progenitors lose M ̇ < 10 − 4 M ⊙ yr − 1 up to a few years before explosion. We show that the overall observed breakout radius distribution is skewed to higher radii due to a luminosity bias. We argue that the 66 − 22 + 11 % of red supergiants (RSGs) explode as SNe II with breakout radii consistent with the observed distribution of RSGs, with a tail extending to large radii, likely due to the presence of CSM.
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