SIRIUS Camera Research Articles

Evaluation of Higher Order Aberrations and Anterior Segment Parameters Changes After Implantable Collamer Lens Implantation for High Myopia.

To evaluate changes in higher order aberrations (HOAs) induced by implantable collamer lens (ICL) implantation in correction of high myopia and to compare the anterior segment parameters before and after surgery. Also, to correlate these parameters with HOAs, the best corrected visual acuity (BCVA) and intraocular pressure (IOP). This prospective interventional cohort case series study included 40 eyes with high myopia that underwent ICL V4c implantation. They were evaluated pre-operatively and post-operatively at 1st and 3rd month HOAs using Scheimpflug Sirius Camera. The anterior segment parameters were evaluated by optical biometry. Correlations between HOAs, BCVA and anterior segment parameters were evaluated. The mean pre-operative BCVA was 0.67 ± 0.17, while post-operative BCVA was 0.74 ± 0.16 (p-value < 0.001). The spherical equivalent was -13.66 ± 2.23 pre-operatively, while post-operatively it was -0.77 ± 0.65 (p-value < 0.001). The mean pre-operative root mean square (RMS) of HOAs was 0.62 ± 0.11 µm, while mean post-operative RMS in the 1st month was 0.82 ± 0.29 µm (p-value < 0.001). At 3rd month, it was 0.63 ± 0.17 µm (p-value = 0.685). The mean pre-operative anterior chamber depth (ACD) was 3.66 ± 0.26 mm. It decreased in the post-operative 1st month to 3.46 ± 0.30 mm, while in 3rd month 3.45 ± 0.24 mm (p-value < 0.001, < 0.001) respectively. The mean pre-operative anterior chamber angle (ACA) 45.98 ± 8.39 o while, the mean ACA was 31.65 ± 4.14, 31.03 ± 3.74 post-operatively (p-value < 0.001, < 0.001) respectively. There was significant increase in IOP (p-value < 0.001). ICL implantation is safe and effective in correction of high myopia, as HOAs increase at first month post-operatively then, return to the pre-operative level by 3rd month. However, anterior segment parameters show significant changes which may need longer follow up.

Correlation between the graft-host junction of penetrating keratoplasty by anterior segment-optical coherence tomography and the magnitude of postoperative astigmatism.

Purpose:This study aimed to evaluate the alignment pattern of the graft–host junction after penetrating keratoplasty (PK) by anterior segment-optical coherence tomography (AS-OCT) and to correlate this pattern with the magnitude of postoperative astigmatism.Methods:This retrospective observational study was carried out on forty patients who underwent PK from February 2013 to August 2014. AS-OCT was performed, and the graft–host junctions were classified into well-apposed junction, malapposed junction, and equally apposed junction. Mal-apposition is subdivided into gap and protrusion. The correlations between clinical characteristics, wound profiles from the AS-OCT, and the magnitude of postoperative astigmatism by Sirius camera (Costruzione Strumenti Oftalmici [CSO], Florence, Italy (CSO, Sirius), were analyzed.Results:Graft–host junctions from forty patients were analyzed; 18 eyes had well-apposed junctions, ten eyes had malapposed junctions, and 12 had equally apposed junctions. The mean cylinder was −9.44 ± −4.00D in well-apposed group, −13.40 ± −5.01D in malapposed group, and −4.67 ± −0.94D in equally apposed group. Alignment pattern of the graft–host junction correlated significantly with the magnitude of astigmatism (P = 0.034). Preoperative corneal diseases did not have an effect on the magnitude of astigmatism (P = 0.123).Conclusion:The alignment pattern of the graft–host junction by AS-OCT can explain the postoperative astigmatism after PK where it correlates significantly with the magnitude of astigmatism.

Deep NIR photometry of H i galaxies in the Zone of Avoidance

Current studies of the peculiar velocity flow field in the Local Universe are limited by either the lack of detection or accurate photometry for galaxies at low Galactic latitudes. The contribution to the dynamics of the Local Group of the largely unknown mass distribution in this 'Zone of Avoidance' remains controversial. We present here the results of a pilot project to obtain deep near infrared (NIR) observations of galaxies detected in the systematic Parkes deep HI survey of the ZoA - 578 galaxies with recession velocities out to 6000 km/s were observed with the 1.4m InfraRed Survey Facility SIRIUS camera providing J, H and K_s imaging ~2 mag deeper than 2MASS. After star-subtraction, the resulting isophotal magnitudes and inclinations of ZoA galaxies are of sufficient accuracy (magnitude errors under 0.1 mag even at high extinction) to ultimately be used to determine cosmic flow fields "in" the ZoA via the NIR Tully-Fisher relation. We further used the observed NIR colours to assess the ratio of the true extinction to the DIRBE/IRAS extinction deep into the dust layers of the Milky Way. The derived ratio was found to be 0.87 across the HIZOA survey region with no significant variation with Galactic latitude or longitude. This value is in excellent agreement with the completely independently derived factor of 0.86 by Schlafly & Finkbeiner based on Sloan data far away from the Milky Way.

MULTI-COLOR TRANSIT PHOTOMETRY OF GJ 1214b THROUGHBJHKsBANDS AND A LONG-TERM MONITORING OF THE STELLAR VARIABILITY OF GJ 1214

We present 5 new transit light curves of GJ 1214b taken in BJHKs-bands. Two transits were observed in B-band using the Suprime-Cam and the FOCAS instruments onboard the Subaru 8.2m telescope, and one transit was done in JHKs-bands simultaneously with the SIRIUS camera on the IRSF 1.4m telescope. MCMC analyses show that the planet-to-star radius ratios are, Rp/Rs = 0.11651 \pm 0.00065 (B-band, Subaru/Suprime-Cam), Rp/Rs = 0.11601 \pm 0.00117 (B-band, Subaru/FOCAS), Rp/Rs = 0.11654 \pm 0.00080 (J-band, IRSF/SIRIUS), Rp/Rs = 0.11550 ^{+0.00142}_{-0.00153} (H-band, IRSF/SIRIUS), and Rp/Rs = 0.11547 \pm 0.00127 (Ks-band, IRSF/SIRIUS). The Subaru Suprime-Cam transit photometry shows a possible spot-crossing feature. Comparisons of the new transit depths and those from previous studies with the theoretical models by Howe & Burrows (2012) suggest that the high molecular weight atmosphere (e.g., 1% H$_2$O + 99% N$_2$) models are most likely, however, the low molecular weight (hydrogen dominated) atmospheres with extensive clouds are still not excluded. We also report a long-term monitoring of the stellar brightness variability of GJ 1214 observed with the MITSuME 50cm telescope in g'-, Rc-, and Ic-bands simultaneously. The monitoring was conducted for 32 nights spanning 78 nights in 2012, and we find a periodic brightness variation with a period of Ps = 44.3 \pm 1.2 days and semi-amplitudes of 2.1% \pm 0.4% in g'-band, 0.56% \pm 0.08% in Rc-band, and 0.32% \pm 0.04% in Ic-band.

IRSF SIRIUS JHKs Simultaneous Transit Photometry of GJ 1214b

Abstract We report on the high-precision transit photometry of GJ 1214b in JHK$ _{\rm s}$ bands simultaneously taken with the SIRIUS camera on the Infrared Survey Facility 1.4 m telescope located in Sutherland, South Africa. Our Markov-Chain Monte Carlo analysis shows that observed planet-to-star radius ratios in the JHK$ _{\rm s}$ bands are $ R_{\rm p}/R_{{\rm s},J}$$ =$ 0.11833 $ \pm$ 0.00077, $ R_{\rm p}/R_{{\rm s},H}$$ =$ 0.11522 $ \pm$ 0.00079, and $ R_{\rm p}/R_{{\rm s},K_{\rm s}}$$ =$ 0.11459 $ \pm$ 0.00099, respectively. The radius ratios are very consistent with previous studies by Bean et al. (2011, ApJ, 743, 92) within 1 $ \sigma$ , while our ratio in the K$ _{\rm s}$ band is shallower than previous measurements in the same band by Croll et al. (2011, ApJ, 736, 78) and inconsistent even at the 4 $ \sigma$ level with them. We have no satisfactory explanation for this discrepancy at this point. Our overall results support a flat transmission spectrum in the observed bands, which can be explained by a water-dominated atmosphere or an atmosphere with extensive high-altitude clouds or haze. To explain the discrepancy of the radius ratios, and to determine a definitive atmosphere model for GJ 1214b in the future, more extended transit observations in around the K$ _{\rm s}$ band would be especially important.

INTERSTELLAR EXTINCTION LAW TOWARD THE GALACTIC CENTER III:J,H,KSBANDS IN THE 2MASS AND THE MKO SYSTEMS, AND 3.6, 4.5, 5.8, 8.0 μm IN THESPITZER/IRAC SYSTEM

We have determined interstellar extinction law toward the Galactic center (GC) at the wavelength from 1.2 to 8.0 micron, using point sources detected in the IRSF/SIRIUS near-infrared survey and those in the 2MASS and Spitzer/IRAC/GLIMPSE II catalogs. The central region |l| < 3deg and |b| < 1deg has been surveyed in the J, H and Ks bands with the IRSF telescope and the SIRIUS camera whose filters are similar to the Mauna Kea Observatories (MKO) near-infrared photometric system. Combined with the GLIMPSE II point source catalog, we made Ks versus (Ks - lambda) color-magnitude diagrams where lambda = 3.6, 4.5, 5.8, and 8.0 micron. The Ks magnitudes of bulge red clump stars and the (Ks - lambda) colors of red giant branches are used as a tracer of the reddening vector in the color-magnitude diagrams. From these magnitudes and colors, we have obtained the ratios of total to selective extinction A(Ks)/E(Ks-lambda) for the four IRAC bands. Combined with A(lambda)/A(Ks) for the J and H bands derived by Nishiyama et al., we obtain A(J):A(H):A(Ks):A([3.6]):A([4.5]):A([5.8]):A([8.0])=3.02:1.73:1:0.50:0.39:0.36:0.43 for the line of sight toward the GC. This confirms the flattening of the extinction curve at lambda > 3 micron from a simple extrapolation of the power-law extinction at shorter wavelengths, in accordance with recent studies. The extinction law in the 2MASS JHKs bands has also been calculated, and a good agreement with that in the MKO system is found. In nearby molecular clouds and diffuse interstellar medium, the lack of reliable measurements of the total to selective extinction ratios hampers unambiguous determination of the extinction law; however, observational results toward these lines of sight cannot be reconciled with a single extinction law.

The Interstellar Extinction Law toward the Galactic Center. II.V,J,H, andKsBands

We have determined the ratios of total to selective extinction directly from observations in the optical V band and near-infrared J band toward the Galactic center. The OGLE (Optical Gravitational Lensing Experiment) Galactic bulge fields have been observed with the SIRIUS camera on the Infrared Survey Facility telescope, and we obtain AV/EV–J = 1.251 ± 0.014 and AJ/EV–J = 0.225 ± 0.007. From these ratios, we derive AJ/AV = 0.188 ± 0.005; combining this with the near-infrared extinction ratios obtained in Paper I for more reddened fields near the Galactic center, we obtain AV:AJ:AH:AKs = 1:0.188:0.108:0.062, which implies steeply declining extinction toward longer wavelengths. In particular, it is striking that the Ks-band extinction is ≈1/16 the visual extinction AV, much smaller than the 1/10 usually employed.

The Distance to the Galactic Center Derived from Infrared Photometry of Bulge Red Clump Stars

On the basis of the near infrared observations of bulge red clump stars near the Galactic center, we have determined the galactocentric distance to be R_0 = 7.52 +- 0.10 (stat) +- 0.35 (sys) kpc. We observed the red clump stars at |l| < 1.0 deg and 0.7 deg < |b| < 1.0 deg with the IRSF 1.4 m telescope and the SIRIUS camera in the H and Ks bands. After extinction and population corrections, we obtained (m - M)_0 = 14.38 +- 0.03 (stat) +- 0.10 (sys). The statistical error is dominated by the uncertainty of the intrinsic local red clump stars' luminosity. The systematic error is estimated to be +- 0.10 including uncertainties in extinction and population correction, zero-point of photometry, and the fitting of the luminosity function of the red clump stars. Our result, R_0 = 7.52 kpc, is in excellent agreement with the distance determined geometrically with the star orbiting the massive black hole in the Galactic center. The recent result based on the spatial distribution of globular clusters is also consistent with our result. In addition, our study exhibits that the distance determination to the Galactic center with the red clump stars, even if the error of the population correction is taken into account, can achieve an uncertainty of about 5%, which is almost the same level as that in recent geometrical determinations.

Interstellar Extinction Law in theJ,H, andKsBands toward the Galactic Center

We have determined the ratios of total to selective extinction in the near-infrared bands (J,H,Ks) toward the Galactic center from the observations of the region l 20 and 05 b 10 with the IRSF telescope and the SIRIUS camera. Using the positions of red clump stars in color-magnitude diagrams as a tracer of the extinction and reddening, we determine the average of the ratios of total to selective extinction to be A/E = 1.44 ± 0.01, A/E = 0.494 ± 0.006, and AH/EJ-H = 1.42 ± 0.02, which are significantly smaller than those obtained in previous studies. From these ratios, we estimate that AJ : AH : A = 1 : 0.573 ± 0.009 : 0.331 ± 0.004 and EJ-H/E = 1.72 ± 0.04, and we find that the power law Aλ ∝ λ-1.99±0.02 is a good approximation over these wavelengths. Moreover, we find a small variation in A/E across our survey. This suggests that the infrared extinction law changes from one line of sight to another, and the so-called universality does not necessarily hold in the infrared wavelengths.

A Distinct Structure inside the Galactic Bar

We present the result of a near-infrared (JHKs) survey along the Galactic plane, -105 ≤ l ≤ 105 and b = +1°, with the IRSF 1.4 m telescope and the SIRIUS camera. Ks versus H - Ks color-magnitude diagrams reveal a well-defined population of red clump stars whose apparent magnitude peak changes continuously along the Galactic plane, from Ks = 13.4 at l = -10° to Ks = 12.2 at l = 10° after dereddening. This variation can be explained by the barlike structure found in previous studies, but we find an additional inner structure at l 4°, where the longitude-apparent magnitude relation is distinct from the outer bar and where the apparent magnitude peak changes by only ≈0.1 mag over the central 8°. The exact nature of this inner structure is as yet uncertain.

Study of the Nuclear Bulge region of the Galaxy

A near infrared survey of the inner 300pc of Nuclear Bulge region of the Milky Way is being carried out as a core program of the SIRIUS Camera mounted on the IRSF telescope at the South African Astronomical Observatory, Sutherland. The SIRIUS camera has three 1K × 1K detectors for simultaneous imaging in the J, H and Ks bands. With pixel scale of 0.45″ and good seeing most of the time, these observations present the deepest views of a large area of the Nuclear Bulge. The aim of this survey is to overcome the incompleteness and confusion limited nature of the undersampled near infrared surveys, such as DENIS and 2MASS in order to get better estimate of the extinction in these lines of sight and distinguish between various stellar populations. Preliminary results from the survey demonstrate the capability of the camera and photometric procedures for the crowded fields.

Deep Near-Infrared Surveys and Young Brown Dwarf Populations in Star-Forming Regions

We are currently conducting three kinds of IR surveys of star forming regions (SFRs) in order to seek for very low-mass young stellar populations. First is a deep JHKs-bands (simultaneous) survey with the SIRIUS camera on the IRSF 1.4m or the UH 2.2m telescopes. Second is a very deep JHKs survey with the CISCO IR camera on the Subaru 8.2m telescope. Third is a high resolution companion search around nearby YSOs with the CIAO adaptive optics coronagraph IR camera on the Subaru. In this contribution, we describe our SIRIUS camera and present preliminary results of the ongoing surveys with this new instrument.