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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').

22236 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  2. EP240506a: Xinglong optical upper limit
  3. GRB 240504A: Fermi GBM Observation
  4. EP240506a: Archival radio searching
  5. EP240506a: TRT optical upper limit
  6. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  7. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  8. EP240506a: Optical upper limit with Kinder observations
  9. IPN triangulation of GRB 240504A
  10. GRB 240502A: 1.3m DFOT Optical upper limit
  11. EP240506a: EP-WXT detection of a new fast X-ray transient
  12. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  13. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  14. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  15. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  16. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  17. Fermi trigger No 736461232: Global MASTER-Net observations report
  18. GW170817: VLA observations at ~5.5 yrs since merger
  19. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
  20. GRB 240502A: Fermi GBM Observation
  21. GRB 240415A 1.3m DFOT Optical upper limit
  22. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  23. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  24. GRB 240426A: VZLUSAT-2 detection
  25. GRB 240425A: VZLUSAT-2 detection
  26. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  27. GRB 240501B: AstroSat CZTI detection
  28. GRB 240501A: Fermi GBM Final Real-time Localization
  29. GRB 240408B: VZLUSAT-2 detection
  30. GRB 240407A: VZLUSAT-2 detection
  31. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  33. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  35. Additional DECam GW-MMADS Candidates from three nights of observations
  36. Fermi-LAT gamma-ray observations of IceCube-240424A
  37. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  38. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  39. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  40. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  41. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  42. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  44. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  45. EP240426b: AST3-2 optical upper limit
  46. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  47. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  48. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  49. EP240426b: EP-WXT detection of a new fast X-ray transient
  50. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  51. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  52. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  53. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  54. GRB 240426A: AstroSat CZTI detection
  55. XMM-Newton observation of EP240426a
  56. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  57. GRB 240414A: NOEMA detection
  58. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  59. EP240426a: GMG optical upper limit
  60. LVK S240422ed: Further Swift-XRT followup of three sources
  61. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  62. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  63. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  64. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
  65. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  66. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  67. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  68. LIGO/Virgo/KAGRA S240422ed: Upper limits from GECAM Observations
  69. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA and Kilonova-Catcher galaxy targeting observations
  70. LIGO/Virgo/KAGRA S240422ed: Additional DECam GW-MMADS Candidates from the first two nights of observations
  71. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
  72. GRB 240419B: Swift-BAT refined analysis
  73. GRB 240421B: Swift-BAT refined analysis
  74. GRB 240422A: Glowbug gamma-ray detection
  75. LIGO/Virgo/KAGRA S240422ed: Archival BlackGEM/MeerLICHT detections of AT 2024hdr & AT 2024hdq
  76. LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
  77. LIGO/Virgo/KAGRA S240422ed: No significant counterpart candidates in HAWC observations
  78. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  79. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  80. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  81. LIGO/Virgo/KAGRA S240422ed: Early X-ray Upper Limits from EP-WXT for the LVK Sky Localization Region
  82. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of Mag24a
  83. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  84. LIGO/Virgo/KAGRA S240422ed: Archival DECaPSs2 observations of the field of Mag24a
  85. LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
  86. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
  87. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  88. LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
  89. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  90. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  91. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  92. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  93. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  94. GRB 240419A: Swift-BAT refined analysis
  95. GRB 240418A: Swift-BAT refined analysis
  96. LXT240402A/GRB240402B: Chandra X-ray detection
  97. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  98. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  99. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  100. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations

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