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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').

22276 results found.

  1. EP240518a: EP-WXT detection of a new X-ray transient
  2. LIGO/Virgo/KAGRA S240514c: Updated Sky localization
  3. GRB 240516A: Swift-BAT refined analysis
  4. IPN triangulation of GRB 240514B (short)
  5. GRB 240516A: Swift-XRT refined Analysis
  6. GRB 240516A: Fermi GBM Observation
  7. GRB 240511A: Observations from GTC/OSIRIS+
  8. GRB 240516A: Swift detection of a burst
  9. GRB 240511A: radio detection of afterglow candidate
  10. MAXI GRB240514.78: Global MASTER-Net observations report
  11. GRB 240514E: MAXI/GSC detection of a probable afterglow
  12. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  13. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  14. GRB 240513A: Fermi GBM observation
  15. GRB 240513A: Swift-XRT observations
  16. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  17. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  19. transient: Xinglong Nearby Galaxy Supernova Survey detection of AT2024iss
  20. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  22. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  23. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  24. GRB 240511A: Fermi GBM Observation
  25. GRB 240511A: Swift-BAT refined analysis
  26. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  27. GRB 240511A: J-band observations with WINTER
  28. Fermi trigger No 737247400: Global MASTER-Net observations report
  29. Fermi trigger No 737168073: Global MASTER-Net observations report
  30. GRB 240511A: Enhanced Swift-XRT position
  31. GRB 240511A : MITSuME Akeno optical upper limits
  32. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  33. GRB 240511A: Swift-XRT refined Analysis
  34. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  35. GRB 240511A: Swift detection of a burst
  36. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  37. Fermi trigger No 737111207: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  40. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  41. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  42. EP240506a: Xinglong optical upper limit
  43. GRB 240504A: Fermi GBM Observation
  44. EP240506a: Archival radio searching
  45. EP240506a: TRT optical upper limit
  46. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  47. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  48. EP240506a: Optical upper limit with Kinder observations
  49. IPN triangulation of GRB 240504A
  50. GRB 240502A: 1.3m DFOT Optical upper limit
  51. EP240506a: EP-WXT detection of a new fast X-ray transient
  52. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  54. GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  55. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  56. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  57. Fermi trigger No 736461232: Global MASTER-Net observations report
  58. GW170817: VLA observations at ~5.5 yrs since merger
  59. GRB 240504A: BALROG localization (Fermi Trigger 736492377 / GRB 240504217)
  60. GRB 240502A: Fermi GBM Observation
  61. GRB 240415A 1.3m DFOT Optical upper limit
  62. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  63. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  64. GRB 240426A: VZLUSAT-2 detection
  65. GRB 240425A: VZLUSAT-2 detection
  66. MeerKAT Discovery of a Probable Radio Counterpart to EP240414a
  67. GRB 240501B: AstroSat CZTI detection
  68. GRB 240501A: Fermi GBM Final Real-time Localization
  69. GRB 240408B: VZLUSAT-2 detection
  70. GRB 240407A: VZLUSAT-2 detection
  71. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  73. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  75. Additional DECam GW-MMADS Candidates from three nights of observations
  76. Fermi-LAT gamma-ray observations of IceCube-240424A
  77. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  78. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  79. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  80. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  81. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  82. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  84. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  85. EP240426b: AST3-2 optical upper limit
  86. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  87. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  88. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  89. EP240426b: EP-WXT detection of a new fast X-ray transient
  90. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  91. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  92. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  93. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  94. GRB 240426A: AstroSat CZTI detection
  95. XMM-Newton observation of EP240426a
  96. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate
  97. GRB 240414A: NOEMA detection
  98. LIGO/Virgo/KAGRA S240422ed: EP240426a possible optical detection
  99. EP240426a: GMG optical upper limit
  100. LVK S240422ed: Further Swift-XRT followup of three sources

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