The phrase "a magnitude around" is correct and usable in written English.
It can be used when discussing measurements, estimates, or approximations in various contexts, such as science, engineering, or statistics.
Example: "The earthquake registered a magnitude around 6.5 on the Richter scale."
Alternatives: "approximately a magnitude of" or "about a magnitude of".
Varying by a quarter of a magnitude around an average apparent magnitude of 4.83 every seven hours, the star system lies 98 light years away.
Even when in conjunction with the Sun, Vesta will have a magnitude around +8.5; thus from a pollution-free sky it can be observed with binoculars even at elongations much smaller than near opposition.
When an intense femtosecond laser pulse was focused on culture medium under a microscope, a local explosion of the culture medium was induced at the laser focal point, and a resultant stress wave, with a magnitude around micro-Newton, propagated at the vicinity of the laser focal point (Hosokawa et al., 2011).
Compounds 9, 11, and 13 inhibited the function of topoisomerase II more strongly than etoposide with almost same magnitude (around 90% and 30% inhibition at 100 and 20 μM, respectively) which were higher than those of etoposide (72% and 18% inhibition).
The linear slopes for the different sample types differ by one order of magnitude (around 0.1 for pure MCYST-LR, 1 for Stigeoclonium sp. extract and around 4 for salmon hydrolyzate for normalized data).
In the control case, the frequency of spikes increased linearly with increasing current and reached a maximal frequency of around 20 Hz when the current steps had a magnitude of around 300 pA (Figure 9-B, gray line, right axis).
In the aftershock interferogram (Fig. 5a), we also noticed movement away from the satellite with an amplitude of around 8 cm, which was also observed in the same areas, even for the shock with a magnitude of around 5 (Mw).
The seismic structure at the northern end of the eastern KPR transition is very important for locating the western limit of the future Nankai megathrust earthquake with a magnitude of around 9 (Cabinet Office of Japan 2012).
At a conjunction Ceres has a magnitude of around +9.3, which corresponds to the faintest objects visible with 10×50 binoculars.
At most oppositions, Hygiea has a magnitude of around +10.2, which is as much as four orders fainter than Vesta, and it will require at least a 4 inches telescope to resolve.
At most oppositions, however, Juno only reaches a magnitude of around +8.7 —only just visible with binoculars and at smaller elongations a 3 inches telescope will be required to resolve it.
