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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').

22274 results found.

  1. GRB 240516A: Swift-XRT refined Analysis
  2. GRB 240516A: Fermi GBM Observation
  3. GRB 240511A: Observations from GTC/OSIRIS+
  4. GRB 240516A: Swift detection of a burst
  5. GRB 240511A: radio detection of afterglow candidate
  6. MAXI GRB240514.78: Global MASTER-Net observations report
  7. GRB 240514E: MAXI/GSC detection of a probable afterglow
  8. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  9. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  10. GRB 240513A: Fermi GBM observation
  11. GRB 240513A: Swift-XRT observations
  12. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  13. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  15. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  16. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  17. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  18. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  19. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  20. GRB 240511A: Fermi GBM Observation
  21. GRB 240511A: Swift-BAT refined analysis
  22. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  23. GRB 240511A: J-band observations with WINTER
  24. Fermi trigger No 737247400: Global MASTER-Net observations report
  25. Fermi trigger No 737168073: Global MASTER-Net observations report
  26. GRB 240511A: Enhanced Swift-XRT position
  27. GRB 240511A : MITSuME Akeno optical upper limits
  28. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  29. GRB 240511A: Swift-XRT refined Analysis
  30. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  31. GRB 240511A: Swift detection of a burst
  32. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  33. Fermi trigger No 737111207: Global MASTER-Net observations report
  34. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  36. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  37. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  38. EP240506a: Xinglong optical upper limit
  39. GRB 240504A: Fermi GBM Observation
  40. EP240506a: Archival radio searching
  41. EP240506a: TRT optical upper limit
  42. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  43. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  44. EP240506a: Optical upper limit with Kinder observations
  45. IPN triangulation of GRB 240504A
  46. GRB 240502A: 1.3m DFOT Optical upper limit
  47. EP240506a: EP-WXT detection of a new fast X-ray transient
  48. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  50. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  51. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  52. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  53. Fermi trigger No 736461232: Global MASTER-Net observations report
  54. GW170817: VLA observations at ~5.5 yrs since merger
  55. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
  56. GRB 240502A: Fermi GBM Observation
  57. GRB 240415A 1.3m DFOT Optical upper limit
  58. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  59. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  60. GRB 240426A: VZLUSAT-2 detection
  61. GRB 240425A: VZLUSAT-2 detection
  62. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  63. GRB 240501B: AstroSat CZTI detection
  64. GRB 240501A: Fermi GBM Final Real-time Localization
  65. GRB 240408B: VZLUSAT-2 detection
  66. GRB 240407A: VZLUSAT-2 detection
  67. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  69. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  71. Additional DECam GW-MMADS Candidates from three nights of observations
  72. Fermi-LAT gamma-ray observations of IceCube-240424A
  73. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  74. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  75. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  76. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  77. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  78. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  80. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  81. EP240426b: AST3-2 optical upper limit
  82. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  83. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  84. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  85. EP240426b: EP-WXT detection of a new fast X-ray transient
  86. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  87. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  88. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  89. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  90. GRB 240426A: AstroSat CZTI detection
  91. XMM-Newton observation of EP240426a
  92. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  93. GRB 240414A: NOEMA detection
  94. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  95. EP240426a: GMG optical upper limit
  96. LVK S240422ed: Further Swift-XRT followup of three sources
  97. LIGO/Virgo/KAGRA S240426s: Identification of a GW compact binary merger candidate
  98. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  99. LIGO/Virgo/KAGRA S240422ed: PRIME near-infrared observations
  100. LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190

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